ES2875786T3 - SRS Transmission Using Multiple Component Carriers - Google Patents

Abstract

A method (1800) for wireless communications by a base station, BS, comprising: identifying (1802) a plurality of component carriers, CC, available to at least one user equipment, UE, for use in transmitting reference signals of polling, SRS, to the BS; determining (1804) a configuration comprising a plurality of SRS groups, each SRS group specifying one or more different CCs of the plurality of CCs that the at least one UE is to use for SRS transmissions; and signaling (1808) an indication of the configuration to the at least one UE.

Description

DESCRIPTION

SRS Transmission Using Multiple Component Carriers

CROSS REFERENCE WITH RELATED REQUESTS

[0001] This application claims the benefit of US Provisional Patent Application Serial No. 62 / 402,915, filed September 30, 2016, and US Patent Application No. 15 / 619,094, filed on June 9, 2017, both assigned to the transferee.

BACKGROUND

I. Field of disclosure

[0002] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to methods and apparatus for improving physical random access channel (PRACH) switching and / or probing reference signal. (SRS), for example, methods and apparatus for transmitting PRACH for SRS switching between component carriers.

II. Description of Related Art

[0003] Wireless communication systems are widely implemented to provide various telecommunication services, such as telephony, video, data, messaging and broadcasting. Typical wireless communication systems can employ multiple access technologies that can support communication with multiple users by sharing available system resources (eg, bandwidth, transmission power). Examples of such multiple access technologies include Long Term Evolution (LTE) systems, Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, frequency division (FDMA), orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and synchronous code division time division multiple access systems (TD-SCDMA).

[0004] A wireless communication network can include a number of base stations (BS) that can support communication for a number of user equipments (UE). A UE can communicate with a BS via the downlink and the uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS can be referred to as a Node B, eNB, gNB, Access Point (AP), Radio Headend, Transmission Receive Point (TRP), New Radio BS (NR ), 5G node B, etc.

[0005] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that allows different wireless devices to communicate on a municipal, national, regional and even global level. An example of an emerging telecommunication standard is the new radio (NR), for example 5G radio access. The NR is a set of enhancements to the LTE mobile communication standard promulgated by the Third Generation Collaborative Project (3GPP). It is designed to better support mobile broadband Internet access by improving spectral efficiency, reducing costs, improving services, taking advantage of new spectrum, and better integrating with other open standards that use OFDMA with a cyclic prefix (CP) on the link. downlink (DL) and uplink (UL), as well as to support beamforming, multi-input multiple-output (MIMO) antenna technology, and carrier aggregation. However, as the demand for mobile broadband access continues to increase, there is a need for further improvements in NR technology. Preferably, these enhancements should be applicable to other multiple access technologies and to telecommunication standards that employ these technologies.

[0006] In some networks (eg LTE), a UE can be configured with multiple component (CC) carriers for carrier aggregation. Each CC can be configured for uplink only transmission, downlink only transmission, or uplink and downlink transmission. For CCs that support both uplink and downlink, feedback based on transmit diversity (e.g. with SRS) is beneficial as channel reciprocity can be used (e.g. by BS) to estimate the downlink channel based on the feedback. However, the UE may be able to add a greater number of downlink CCs than uplink CCs. As a result, if the UE is limited to transmitting SRS on configured uplink CCs, there may be some CCs with downlink transmission for the UE that may not have uplink transmission with SRS and thus feedback based in transmit diversity for these carriers based on channel reciprocity between uplink and downlink may not be available.

[0007] In such situations, some networks may support SRS switching to and between CCs to allow the UE to transmit SRS on configured downlink CC (eg uplink not configured) to exploit channel reciprocity. SRS switching, in general, can involve interrupting communication on one DC, switching / retuning to a different DC to transmit SRS, and switching / retuning back to DC after transmitting SRS.

[0008] Furthermore, the UE may not have a valid timing advance (TA) for the transmission of SRS on the downlink CC (for example, the downlink CC may belong to a TA group (TAG) other than of other CCs configured for the UE). In such cases, the Ue may attempt to transmit a PRACH on the downlink CC to obtain an initial TA estimate for the SRS transmission. However, the transmission of PRACH on the downlink DC can also disrupt communication on another DC (for example, similar to the transmission of SRS). This additional interruption due to the PRACH transmission (s) can have a significant impact on performance and communications on the other DC. Consequently, techniques to improve the random access procedure, for example, for SRS switching, may be desirable.

[0009] Furthermore, in general, the UE can be activated to transmit SRS on a periodic or aperiodic basis. However, such conventional trigger mechanisms are generally not capable of jointly triggering SRS transmissions and performing power control for SRS transmissions. Consequently, techniques for jointly activating SRS transmissions and performing power control of SRS transmissions may be desirable.

[0010] Document US 2013/156014 A1 refers to a method and terminal apparatus involving the transmission of an SRS based on probing reference signal (SRS) activation in a wireless communication system. The terminal apparatus of the present invention comprises a receiver that receives, from a base station, an SRS activation indicator to activate an SRS transmission, and a transmitter that transmits the SRS by means of a pre-configured uplink subframe in accordance with the SRS on indicator.

[0011] WO 2012/044846 A1 discloses a wireless communication method that includes receiving overlay information that triggers aperiodic sounding reference signal (SRS) transmission. The method also includes processing the overlay information in accordance with the received activation information. The overlay information may comprise consequential configuration information for the aperiodic SRS transmission, in which case the processing includes transmitting an aperiodic SRS in accordance with the configuration information. When the overlay information has different settings for aperiodic SRS transmission, the processing includes treating the overlay information as an error event. The overlay information may be a trigger received on an uplink grant and a trigger received on a downlink grant. The wireless system may be a multi-carrier system that includes multiple component carriers.

BRIEF EXPLANATION

[0012] The invention is defined by the independent claims. The embodiments of the invention are further defined by the dependent claims. The systems, procedures, and devices of the disclosure each have several aspects, none of which is solely responsible for their desirable attributes. Without limiting the scope of the present disclosure as expressed by the claims that follow, some characteristic features will now be briefly discussed. After considering this discussion and, in particular, after reading the section entitled "Detailed Description", it will be understood how the characteristic features of the present disclosure provide advantages including improved communications between access points and stations in a wireless network.

[0013] Certain aspects of the present disclosure generally refer to one or more enhancements for PRACH and / or SRS switching in a wireless network.

[0014] In certain aspects, the techniques presented herein can improve the random access procedure for switching SRS to the allow the UE transmit a PRACH in the initial symbols (or first) of a timeslot pilot uplink (UpPTS) of a special subframe. For example, in some networks, the UpPTS can be used for up to six symbols, and a PRACH of two to four symbols may be sufficient to allow the BS to determine the TA estimate. The UE can determine which UpPTS symbols to use for PRACH transmission based on a configuration or indication from the BS. In one aspect, the BS may configure the UE to transmit a PRACH on the first symbols (eg, at least the first two symbols) of UpPTS. In one aspect, the BS may configure the UE to transmit a PRACH on one or more UpPTS symbols excluding one or more of the last symbols (eg, the last two symbols) from UpPTS.

[0015] The UE may interrupt communication in a first CC to switch from the first CC to a second CC. After switching to the second CC, the UE can transmit a PRACH on the UpPTS based on the configuration (or indication) received from the BS. By configuring the UE to transmit the PRACH in the first UpPTS symbols, the aspects presented in this document can reduce the impact of switching / interruptions in one (e.g. first) CC due to the transmission of PRACH in another CC ( for example, second downlink only) for the SRS.

[0016] Certain aspects of the present disclosure provide a method for wireless communications that can be performed, for example, by user equipment (UE). The procedure in general includes determining, based on one or more conditions, whether to use one or more symbols from an uplink pilot timeslot (UpPTS) for transmission of a PRACH to a base station (BS). The method also includes breaking communication on a first component carrier (CC) to switch from the first CC to a second CC. The procedure further includes, after switching to the second CC, transmitting the PRACH on the UpPTS based on the determination.

[0017] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes means for determining, based on one or more conditions, whether to use one or more symbols from an UpPTS for transmission from a PRACH to a BS. The apparatus also includes means for interrupting communication in a first CC to switch from the first CC to a second CC. The apparatus further includes means for, after switching to the second CC, transmitting the PRACH on the UpPTS based on the determination.

[0018] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes at least one processor and memory coupled to the at least one processor. The at least one processor is configured to determine, based on one or more conditions, whether to use one or more symbols of an UpPTS for transmission of a PRACH to a BS. The at least one processor is also configured to break communication on a first component carrier (CC) to switch from the first CC to a second CC. The at least one processor is further configured to, after switching to the second CC, transmit the PRACH in the UpPTS based on the determination.

[0019] Certain aspects of the present disclosure provide a computer-readable medium having computer-executable code stored therein for wireless communication that can be performed, for example, by a UE. Computer-executable code generally includes code to determine, based on one or more conditions, whether to use one or more symbols of an UpPTS for transmission from a PRACH to a BS, code to interrupt communication in a first CC to switch from the first CC to a second CC, and code for, after switching to the second CC, transmitting the PRACH on the UpPTS based on the determination.

[0020] Certain aspects of the present disclosure provide a method for wireless communication that can be performed, for example, by a base station (BS). The procedure in general includes determining, based on one or more conditions, whether to configure a UE to use one or more symbols from an UpPTS for transmission of a PRACH to the BS. The procedure also includes transmitting an indication of the determination to the UE. The procedure further includes receiving the PRACH from the UE in the UpPTS.

[0021] Certain aspects of the present disclosure provide an apparatus for wireless, such as a BS communication. The apparatus generally includes means for determining, based on one or more conditions, whether to configure a UE to use one or more symbols from an UpPTS for transmission of a PRACH to the apparatus. The apparatus also includes means for transmitting an indication of the determination to the UE. The apparatus further includes means for receiving from the UE the PRACH in the UpPTS.

[0022] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a BS. The apparatus generally includes at least one processor and memory coupled to the at least one processor. The at least one processor is configured to determine, based on one or more conditions, whether to configure a UE to use one or more symbols from an UpPTS for transmission of a PRACH to the apparatus. The at least one processor is also configured to transmit an indication of the determination to the UE. The at least one processor is further configured to receive the PRACH in the UpPTS from the UE.

[0023] Certain aspects of the present disclosure provide a computer-readable medium having computer-executable code stored therein for wireless communication that can be performed, for example, by a BS. Computer-executable code generally includes code for determining, based on one or more conditions, whether to configure a UE to use one or more symbols from an UpPTS for transmission of a PRACH to the BS, code for transmitting an indication of the determination to the UE, and code to receive the PRACH from the UE in the UpPTS.

[0024] In certain aspects, the techniques presented herein may modify the conventional method of random access to reduce the impact of switching / interruptions in a (e.g. first) CC due to transmission of PRACH in other CC ( e.g. second link only falling). For example, the UE may monitor a physical downlink control channel (PDCCH) command from the BS for a PRACH transmission. The PDCCH command may include resource allocation information for PRACH transmission. After the UE transmits the PRACH, the UE can monitor a random access response (RAR) from the BS. If the RAR is not detected (indicating that the PRACH attempt may have been unsuccessful), the UE can wait for confirmation from the BS before transmitting another PRACH. That is, if the UE does not detect the RAR, the UE can monitor another PDDCH command before transmitting the next PRACH, as opposed to automatically repeating the PRACH transmission as in conventional random access procedures. By having the UE monitor another PDCCH command before transmitting successive PRACHs, the aspects presented herein can reduce the impact of repeated switches / interruptions on one (e.g. first) CC due to successive PRACH transmissions on another CC. (for example, second downlink only) for SRS.

[0025] Certain aspects of the present disclosure provide a method for wireless communication that can be performed, for example, by a UE. The procedure in general includes monitoring a first PDCCH command for a first PRACH transmission. The method also includes determining a transmit power for the first PRACH transmission, based on an indicator received in the first PDCCH command or a retransmission index of the first PRACH transmission. The method further includes transmitting the first PRACH at the determined transmit power. The method even includes, after transmitting the first PRACH, monitoring a second PDCCH command before transmitting a second PRACH.

[0026] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes means for monitoring a first PDCCH command for a first PRACH transmission and means for determining a transmission power for the first PRACH transmission, based on an indicator received on the first PDCCH command or an index of rebroadcasting of the first PRACH broadcast. The apparatus also includes means for transmitting the first PRACH at the determined transmit power. The apparatus further includes means for, after transmitting the first PRACH, monitoring a second PDCCH command before transmitting a second PRACH.

Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes at least one processor and memory coupled to the at least one processor. The at least one processor is configured to monitor a first PDCCH command for a first PRACH transmission and determine a transmission power for the first PRACH transmission, based on an indicator received on the first PDCCH command or a retransmission index. of the first transmission of PRACH. The at least one processor is also configured to transmit the first PRACH at the determined transmit power. The at least one processor is further configured to, after transmitting the first PRACH, monitor a second PDCCH command before transmitting a second PRACH.

[0028] Certain aspects of the present disclosure provide a computer-readable medium having computer-executable code stored therein for wireless communication that can be performed, for example, by a UE. Computer-executable code generally includes code for monitoring a first PDCCH command for a first PRACH transmission, code for determining a transmit power for the first PRACH transmission, based on an indicator received on the first PDCCH command, or a PRACH transmission retransmission index, code for transmitting the first PRACH at the determined transmit power, and code for, after transmitting the first PRACH, monitoring a second PDCCH command before transmitting a second PRACH.

[0029] Certain aspects of the present disclosure provide improved techniques for jointly activating SRS transmissions and performing power control of SRS transmissions. A BS can identify multiple CCs that are available for use by UEs for transmissions from SRS to the BS. The BS may configure a set of SRS activation groups that each include one or more of the multiple CCs that the UE must use for SRS transmissions. The BS may signal an indication of the configuration to the UE. Thus, using the techniques described herein, a BS can trigger SRS transmissions from multiple UEs, trigger SRS transmissions from multiple CCs from the same UE at the same time, and / or perform separate power control for SRS transmissions. from each CC configured for a UE. As such, these techniques can provide greater flexibility and reduced overhead to configure SRS transmissions (with power control) for a UE, compared to traditional SRS trigger mechanisms.

[0030] Certain aspects of the present disclosure provide a method for wireless communication that can be performed, for example, by means of a BS. The general procedure includes identifying a plurality of available Ccs for at least one UE to use for SRS transmissions to the BS. The method also includes determining a configuration that specifies one or more CCs of the plurality of CCs that the at least one UE must use for SRS transmissions. The method further includes signaling an indication of the configuration to the at least one UE.

[0031] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a BS. The apparatus generally includes means for identifying a plurality of CCs available for use by at least one UE for SRS transmissions to the apparatus. The apparatus also includes means for determining a configuration that specifies one or more CCs of the plurality of CCs that the at least one UE must use for SRS transmissions. The apparatus further includes means for signaling an indication of the configuration to the at least one UE.

[0032] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a BS. The apparatus generally includes at least one processor and memory coupled to the at least one processor. The at least one processor is configured to identify a plurality of available CCs for at least one UE to use for SRS transmissions to the apparatus. The at least one processor is also configured to determine a configuration that specifies one or more CCs of the plurality of CCs that the at least one UE must use for SRS transmissions. The at least one processor is further configured to signal a configuration indication to the at least one UE.

[0033] Certain aspects of the present disclosure provide a computer-readable medium having computer-executable code stored therein for wireless communication that can be performed, for example, by a BS. Computer-executable code generally includes code for identifying a plurality of CCs available for at least one UE to use for transmissions from SRS to the BS, code for determining a configuration specifying one or more CCs of the plurality of CCs than the at least one UE must use for SRS transmissions, and code to signal an indication of the configuration to the at least one UE.

[0034] Certain aspects of the present disclosure provide a method for wireless communication that can be performed, for example, by a UE. The method in general includes receiving a trigger to transmit an SRS on each CC of a group of one or more CCs to one or more corresponding BSs. The procedure also includes transmitting SRS to the BSs in response to the trigger.

[0035] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes means for receiving a trigger to transmit an SRS on each CC of a group of one or more CCs to one or more corresponding BSs. The apparatus also includes means for transmitting SRS to the BSs in response to the trigger.

[0036] Certain aspects of the present disclosure provide an apparatus for wireless communication, such as a UE. The apparatus generally includes at least one processor and memory coupled to the at least one processor. The at least one processor is configured to receive a trigger to transmit an SRS on each CC of a group of one or more CCs to one or more corresponding BSs. The at least one processor is also configured to transmit SRS to the BSs in response to the trigger.

[0037] Certain aspects of the present disclosure provide a computer-readable medium having computer-executable code stored therein for wireless communication that can be performed, for example, by a UE. Computer-executable code generally includes code for receiving a trigger to transmit an SRS on each CC in a group of one or more CCs to one or more corresponding BSs, and code for transmitting SRS to the BSs in response to the trigger.

[0038] For the achievement of the foregoing and related purposes, the one or more aspects comprise the characteristic features fully described hereinafter and pointed out in particular in the claims. The following description and accompanying drawings set out in detail certain illustrative characteristic features of the one or more aspects. However, these characteristic features are indicative of only a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the way in which the characteristic features of the present disclosure mentioned above can be understood in detail, a more particular description, briefly summarized above, can be offered by reference to the aspects, of which some are illustrated in the accompanying drawings. However, it should be noted that the attached drawings illustrate only certain typical aspects of the present disclosure and, therefore, are not to be considered as limiting its scope, since the description may admit other equally effective aspects.

FIG. 1 is a block diagram that conceptually illustrates an exemplary telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram conceptually illustrating a link frame structure example downstream in a telecommunications system, in accordance with certain aspects of this disclosure.

FIG. 3 is a diagram illustrating an example uplink frame structure in a telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating a design of an exemplary Node B and User Equipment (UE), in accordance with certain aspects of the present disclosure.

FIG. 5 is a diagram illustrating an exemplary radio protocol architecture for the user and control planes, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates a subframe resource element assignment, in accordance with certain aspects of the present disclosure.

FIG. 7 illustrates an example logical architecture of a distributed radio access network (RAN), in accordance with certain aspects of the present disclosure.

FIG. 8 illustrates an example physical architecture of a distributed RAN, in accordance with certain aspects of this disclosure.

FIG. 9 is a diagram illustrating an example of a downlink (DL) centered subframe, in accordance with certain aspects of the present disclosure.

FIG. 10 is a diagram illustrating an example of an uplink centered (UL) subframe, in accordance with certain aspects of the present disclosure.

FIG. 11 illustrates one type of exemplary continuous carrier aggregation, in accordance with certain aspects of the present disclosure.

FIG. 12 illustrates an exemplary type of non-continuous carrier aggregation, in accordance with certain aspects of the present disclosure.

FIG. 13 is a block diagram illustrating example uplink and downlink subframes for two component carriers (CC), in accordance with certain aspects of the present disclosure.

FIG. 14 is a block diagram illustrating exemplary transmission in a first CC interrupted by transmission of the sounding reference signal (SRS) in a second CC, in accordance with certain aspects of the present disclosure.

FIG. 15 is a flow chart illustrating example operations for wireless communications via a UE, in accordance with certain aspects of the present disclosure.

FIG. 16 is a flow chart illustrating example operations for wireless communications via a BS, in accordance with certain aspects of the present disclosure.

FIG. 17 is a flow chart illustrating example operations for wireless communications via a UE, in accordance with certain aspects of the present disclosure.

FIG. 18 is a flow chart illustrating example operations for wireless communications via a BS, in accordance with certain aspects of the present disclosure.

FIG. 19 is a flow chart illustrating example operations for wireless communications via a UE, in accordance with certain aspects of the present disclosure.

[0040] For ease of understanding, identical reference numerals have been used where possible to designate identical elements that are common to the figures. It is contemplated that the elements disclosed in one aspect may be used to advantage in other aspects without specific mention.

DETAILED DESCRIPTION

[0041] Aspects of the present disclosure provide techniques and apparatus for improving PRACH transmissions for SRS switching situations.

[0042] Typically, in cases where the UE is configured with one or more downlink-only CCs, etc., the UE can perform SRS switching to and between downlink CCs to transmit SRS on (eg, the inactive UL subframes) on the downlink CCs. The SRS transmissions can allow the BS to exploit the channel reciprocity between the uplink and the downlink by estimating the downlink channel quality based on the SRS. In many cases, however, the UE may have a limited number of transmission chains (for example, the UE may have only one transmission chain), and therefore SRS switching may involve the UE switching between transmissions. on one (eg first) CC to SRS transmission on a different (eg downlink only) CC and then back to the first CC. This switching can affect (for example, interrupt) communications on the first DC.

[0043] In addition, before the EU attempt to transmit the SRS in a given CC, the UE may need a valid timing advance (TA) to the CC. However, in cases where the downlink-only CC does not belong to the same timing advance group (TAG) as another CC that is configured for uplink, the UE may not have an initial TA for the CC of only downlink. In such cases, the UE may try to perform a random access procedure to obtain the TA for the downlink-only CC to use for SRS transmissions on the downlink-only CC. However, if the UE has a limited number of transmission chains, the UE may also have to interrupt communication on one (e.g. first) CC to transmit the PRACH on the downlink-only CC (e.g. similar to SRS switching). Such interruption of the (eg, first) CC due to PRACH transmission can have a significant impact on performance, communications, etc., at the first CC. For example, the interruption due to the transmission of PRACH can create additional interruptions or interruptions in the previous and / or subsequent subframes in the first CC.

[0044] In addition, in some cases, initiate a random access procedure in DC single downlink based on a (or conventional) random access procedure inherited may be ineffective and cause numerous interruptions in the first CC. For example, a UE using a legacy random access procedure may automatically attempt to repeat PRACH transmissions (for example, if the UE determines that a previous PRACH was unsuccessful). However, as the UE may have to switch to a second DC to transmit each PRACH, these repeated PRACH transmissions can cause significant interruptions and disturbances to communications on the first DC, reducing performance on the first DC.

[0045] Accordingly, there is a need for further improvements in the random access procedure that can be performed for switching situations SRS.

[0046] The aspects presented herein may enable the UE to use the start (for example, the first symbols) UpPTS in a special subframe for transmitting the PRACH for SRS switching situations. For example, the UE may determine, based on one or more conditions, whether to use one or more initial symbols of an UpPTS for PRACH transmission. The one or more conditions may include at least one of a setting to use the initial UpPTS symbols, an indication to use the initial UpPTS symbols, or an ability of the UE to use the initial UpPTS symbols for transmission of PRACH. After interrupting communication in a first CC to switch from the first CC to a second CC, the UE can transmit the PRACH in the second CC based on the determination. The second CC may be a CC that is configured for downlink transmission only (eg, a CC that is not configured for at least PUSCH / PUCCH transmission). In this way, the Ue can reduce the amount of time communication is interrupted in the first CC due to the transmission of PRACH in the second CC.

[0047] Additionally or alternatively, the aspects presented herein provide a modified random access procedure that the UE can use for CCs that are configured for downlink transmission only to reduce the impact of switching / outages on the first CC. In certain aspects, after the UE transmits a PRACH (for example, based on an initial PDCCH command), the UE may monitor another PDCCH command before transmitting another PRACH (for example, repeating the PRACH transmission) in a second CC. The second CC, for example, may be a CC that is configured for downlink transmission only. In this way, the Ue can avoid causing numerous outages on a first CC due to repeated PRACH transmissions on the second CC (typically associated with legacy random access procedures).

[0048] Aspects of the present disclosure also provide one or more enhancements to activate and manage SRS transmissions. Conventional mechanisms for activating SRS transmission in general cannot jointly activate SRS transmissions and provide power control for SRS transmissions. The techniques presented herein provide flexible and efficient mechanisms that allow a BS (e.g., via group downlink control information (DCI)) to jointly trigger SRS transmissions from one or more UEs, trigger transmissions of SRS from multiple DCs from the same UE and / or perform separate power control for each DC, etc. Many other aspects are provided.

[0049] Hereinafter , various aspects of the disclosure are fully described with reference to the accompanying drawings. However, this disclosure can be made in many different ways and should not be construed to be limited to any specific structure or function presented throughout this disclosure. Rather, these aspects are provided so that this disclosure is comprehensive and complete, and fully conveys the scope of the disclosure to those skilled in the art. Based on the teachings herein, one skilled in the art should appreciate that the scope of the disclosure is intended to encompass any aspect of the disclosure disclosed herein, whether implemented independently of, or in combination with, any other aspect of the disclosure. . For example, an apparatus can be implemented or a method can be practiced using any number of aspects discussed herein. Furthermore, the scope of the disclosure is intended to encompass an apparatus or method that is practiced using other structure, functionality, or structure and functionality, in addition to, or apart from, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be made by one or more elements of a claim.

[0050] The term "exemplary" is used herein to mean "serving as an example, instance or illustration." Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects.

[0051] Although particular aspects are described herein, many variations and permutations of these aspects are within the scope of the disclosure. Although some benefits and advantages of preferred features are mentioned, it is not intended to limit the scope of the disclosure to particular benefits, uses or objectives. Rather, aspects of the disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the figures and in the following description of preferred aspects. The detailed description and drawings are merely illustrative of the disclosure, rather than limiting, and the scope of the disclosure is defined by the appended claims and their equivalents.

[0052] The techniques described herein may be used for various wireless communication networks, such as networks Lt E, CDMA, TDMA, FDMA, OFDMA, s C-FDMA and other. The terms "network" and "system" are often used interchangeably. A CDMA network can implement radio technology, such as Universal Terrestrial Radio Access (UTRA), cdma2000, etc. UTRA includes broadband CDMA (WCDMA), and other variants of CDMA. cdma2000 covers the IS-2000, IS-95 and IS-856 standards. A TDMA network can implement radio technology such as the Global System for Mobile Communications (GSM). An OFDMA network can implement a radio technology such as NR (e.g. RA5G), Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (WiFi), IEEE 802.16 (WiMAX), 802.20 IEEE, OFDMA Flash, etc. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). NR is an emerging wireless communications technology in development alongside the 5G Technology Forum (5GTF). 3GPP Long Term Evolution (LTE) and Advanced LTE (LTE-A) are versions of UMTS that use Eu TrA. UTRA, E-UTRA, UMTS, LTE, LTE-A and GSM are described in documents from an organization called "Third Generation Collaborative Project" (3GPP). cdma2000 and UMB are described in documents from an organization called "Third Generation Second Collaborative Project" (3GPP2). The techniques described herein can be used for the wireless networks and radio technologies mentioned above, as well as for other wireless networks and radio technologies. For clarity, while aspects can be described herein using terminology commonly associated with 3G and / or 4G wireless technologies, aspects of the present disclosure can be applied in communication systems based on another generation, such such as 5G or later, including NR technologies.

EXAMPLE WIRELESS COMMUNICATIONS SYSTEM

[0053] FIG. 1 illustrates an example wireless network 100, in which aspects of the present disclosure can be realized. For example, the wireless network can be a new radio or 5G network. Base station (BS) 110 may comprise an eNB, gNB, a transmit receiving point (TRP), a node B (NB), a 5G NB, an access point (AP), a new radio BS ( NR), etc.

[0054] In some respects, unlike transmitting PRACH on a downlink-only CC according to a legacy random access procedure, the UE 120 can use a modified random access procedure that reduces the impact of outages on a CC due to to PRACH transmissions in another CC for SRS. The modified random access procedure may involve waiting for confirmation from the BS before transmitting successive PRACHs. For example, a UE 120 can monitor a PDCCH command from BS 110 for a PRACH transmission. The u E 120 can transmit a PRACH to the BS 110 based on the information (eg, resource allocation information, number of attempts to transmit PRACH, transmit power, etc.) in the PDCCH command.

[0055] To transmit the PRACH, the UE 120 can interrupt the communication in a first CC to switch from the first CC to a second CC, and transmit the PRACH on the second CC. The second CC may be a CC that is configured for downlink transmission (eg, not configured for at least PUSCH / PUCCH transmissions). After transmitting the PRACH, the UE 120 may monitor a random access response (RAR) from the BS 110. If the RAR is not detected, the UE 120 may monitor another PDCCH command from the BS 110 before repeating the transmission of the PRACH. In this way, the UE 120 can reduce the impact (eg, outages) on the first CC that would otherwise be caused by automatic repeat PRACH attempts made based on an inherited random access procedure.

[0056] Additionally or alternatively, the aspects can reduce the impact on a first DC because switching to a second DC for transmissions PRACH to the allow the UE 120 use the initial symbols of UpPTS for transmitting PRACH in second CC. For example, the UE 120 can determine whether to use the initial UpPTS symbols for PRACH transmission on the second CC. The determination may be based on at least one of a configuration to use the initial UpPTS symbols, an indication to use the initial UpPTS symbols, or an ability of the UE to use the initial UpPTS symbols for transmission of PRACH. After switching to the second CC from the first CC, the UE 120 may transmit a PRACH on the second CC based on the determination. In this way, the UE 120 can reduce the amount of time communication is interrupted in the first CC due to the transmission of PRACH in the second CC.

[0057] Alternatively Additionally or shape, the features presented in the present document allow a BS 110 together active (eg by DCI Group) transmissions SRS from one or more UE 120, active transmissions SRS from multiple DC from the same UE 120 and / or perform separate power control for each DC, etc. Co-activating SRS transmissions and / or performing power control can increase flexibility and / or reduce overhead associated with configuring SRS transmissions for UE (relative to conventional SRS trigger mechanisms).

[0058] As illustrated in FIG. 1, the wireless network 100 may include a number of BS 110s and other network entities. A BS can be a station that communicates with the UE. Each BS 110 can provide communication coverage for a particular geographic area. In 3GPP, the term "cell" can refer to a coverage area of a Node B and / or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the terms "cell" and eNB, gNB, Node B, 5G NB, AP, NR BS, or TRP may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographical area of the cell may be moved in accordance with the location of a mobile base station. In some examples, the base stations may be interconnected with each other and / or with one or more other base stations or network nodes (not shown) in the wireless network 100 through various types of backhaul interfaces, such as a direct physical connection, virtual network or similar using any suitable transport network.

[0059] In general, any number of wireless networks can be implemented in a given geographic area. Each wireless network can support a particular radio access technology (RAT) and can operate on one or more frequencies. A RAT can also be called a radio technology, an air interface, etc. A frequency can also be called a carrier, a frequency channel, etc. Each frequency can support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, 5G NR or RAT networks may be implemented.

[0060] A BS can provide communication coverage for a macrocell, a picocell, a femtocell, and / or other types of cells. A macrocell can cover a relatively large geographic area (for example, several kilometers in radius), and can allow unrestricted access by UE with subscription to the service. A picocell can cover a relatively small geographical area and can allow unrestricted access by UE with subscription to the service. A femtocell can cover a relatively small geographic area (for example, a home) and can allow restricted access to UEs that are associated with the femtocell (for example, UEs of a closed subscriber group (CSG), UEs for users of the home, etc.). A BS for a macrocell can be called a macro BS. A BS for a picocell can be called a BS peak. A BS for a femtocell can be called a femto BS or home BS. In the example shown in FIG. 1, BS 110a, 110b and 110c can be macro BS for macro cells 102a, 102b and 102c, respectively. The BS 110x can be a BS peak for a 102x picocell. BS 110y and 110z can be femto BS for femtocells 102y and 102z, respectively. A BS can support one or multiple cells (for example, three).

[0061] Wireless network 100 may also include relay stations. A relay station is a station that receives a transmission of data and / or other information from an earlier station (for example, a BS or a UE) and sends a transmission of the data and / or other information to a later station (for example, a UE or a BS). A relay station can also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110r can communicate with BS 110a and UE 120r to facilitate communication between BS 110a and UE 120r. A relay station can also be called a relay BS, relay, etc.

The wireless network 100 can be a heterogeneous network that includes BSs of different types, for example, macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different levels of transmit power, different coverage areas, and different impact on interference in the wireless network 100. For example, macro BSs may have a high level of transmit power (for example, of 20 watts), while pico BS, femto BS, and relays may have a lower transmit power level (for example, 1 watt).

[0063] Wireless network 100 can support synchronous or asynchronous operation. For synchronous operation, the BSs can have similar frame timing, and the transmissions from different BSs can be roughly aligned in time. For asynchronous operation, the BSs may have different frame timing, and the transmissions from different BSs may not be time aligned. The techniques described herein can be used in both synchronous and asynchronous operation.

[0064] A network controller 130 can be coupled to a set of BSs and provide coordination and control for these BSs. The network controller 130 can communicate with the BS 110s via a backhaul network. The BS 110s can also communicate with each other, for example, directly or indirectly, via a wireless or wired backhaul network.

[0065] UE 120 (eg 120x, 120y, etc.) can be dispersed throughout the wireless network 100 and each UE can be fixed or mobile. A UE 110 can be called a mobile station, terminal, access terminal, subscriber unit, station, customer local equipment (CPE), mobile phone, smartphone, personal digital assistant (PDA), wireless modem, wireless communication device, handheld device, laptop, cordless phone, wireless local loop station (WLL), tablet, camera, video game device, netbook, smartbook, ultrabook, medical equipment or device, biometric sensor / device, portable device such as smart watch, smart garments, smart glasses, smart wristbands, smart jewelry (for example, smart ring, smart bracelet), entertainment device (for example, music or video device, or satellite radio), vehicle component or sensor, smart meter / sensor , industrial manufacturing equipment, global positioning system device, or any other suitable device that is configured for To communicate through a wireless or wired medium. Some UEs can be considered evolved or machine type communication devices (MTC) or evolved MTC devices (eMTC). UE MTC and eMTC include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that can communicate with a BS, another device (for example, a remote device) or some another entity. A wireless node can provide, for example, connectivity to or to a network (eg, a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs can be considered Internet of Things (IoT) devices.

[0066] In FIG. 1, a solid line with double arrows indicates the desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and / or uplink. A dashed line with a double arrow indicates interfering transmissions between a UE and a BS.

[0067] Certain wireless networks (eg, LTE) use orthogonal frequency division multiplexing (OFDM) on the downlink and single carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM divide the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, intervals, etc. Each subcarrier can be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between contiguous subcarriers can be fixed, and the total number of subcarriers (K) can depend on the system bandwidth. For example, the subcarrier spacing can be 15 kHz and the minimum resource allocation (called a "resource block") can be 12 subcarriers (or 180 kHz). Consequently, the size of a nominal FFT can be equal to 128, 256, 512, 1024, or 2048 for system bandwidths of 1.25, 2.5, 5, 10, or 20 megahertz (MHz), respectively. The system bandwidth can also be divided into subbands. For example, a subband can cover 1.08 MHz (that is, 6 resource blocks) and there can be 1, 2, 4, 8, or 16 subbands for system bandwidths of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

[0068] While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communication systems, such as NR, NR may use OFDM with a CP uplink and downlink and include support for half-duplex operation using TDD. 100MHZ single component carrier bandwidth can be supported. The NR resource blocks can span 12 subcarriers with a subcarrier bandwidth of 75 kHz in a duration of 0.1 ms. Each radio frame can consist of 50 subframes with a length of 10 ms. Consequently, each subframe can be 0.2 ms long. Each subframe can indicate a link direction (ie DL or UL) for data transmission, and the link direction for each subframe can be dynamically switched. Each subframe can include DL / UL data as well as DL / UL control data. Beam shaping can be supported and the beam direction can be dynamically configured. MIMO streams can also be supported with precoding. MIMO configurations on the DL can support up to 8 transmitting antennas with multi-layer DL streams of up to 8 streams and up to 2 streams per UE. Multilayer streams with up to 2 streams per UE can be supported. Multiple cell aggregation with up to 8 serving cells can be supported. Alternatively, the NR may support a different air interface, other than an OFDM-based interface. NR networks can include entities such as central units or distributed units.

[0069] In some examples, access to the air interface can be programmed, in which a programming entity (eg, a base station) allocates resources for communication between some or all of the devices and equipment within its area of service or cell. In the present disclosure, as discussed in more detail below, the scheduling entity may be in charge of scheduling, allocating, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities use the resources assigned by the schedule entity.

[0070] Base stations are not the only entities that can function as a scheduling entity. That is, in some examples, a UE may function as a scheduling entity, scheduling resources for one or more subordinate entities (eg, one or more UEs). In this example, the UE is functioning as a scheduling entity, and other UEs use resources scheduled by the UE for wireless communication. A UE can function as a scheduling entity in a peer-to-peer (P2P) network, and / or in a mesh network. In an example mesh network, UEs may optionally communicate directly with each other in addition to communicating with the scheduling entity.

[0071] Therefore, in a wireless communication network with programmed access to time-frequency resources and having a cellular configuration, a P2P configuration and a mesh configuration, a scheduling entity and one or more subordinate entities can communicate. using scheduled resources.

[0072] FIG. 2 shows a downlink (DL) frame structure used in telecommunications systems (eg, LTE). The transmission timeline for the downlink can be divided into radio frame units. Each radio frame can have a predetermined duration (eg, 10 milliseconds (ms)) and can be divided into 10 subframes with indices from 0 to 9. Each subframe can include two slots. Thus, each radio frame can include 20 slots with indices from 0 to 19. Each slot can include L symbol periods, for example 7 symbol periods for a normal cyclic prefix (as shown in FIG. 2) or 14 symbol periods for an extended cyclic prefix. The 21 symbol periods in each subframe can have indices assigned from 0 to 2L-1. The available time-frequency resources can be divided into resource blocks. Each resource block can span N subcarriers (eg 12 subcarriers) in one slot.

[0073] In certain systems (eg LTE), a BS can send a main sync signal (PSS) and a secondary sync signal (SSS) for each cell in the BS. The primary and secondary sync signals may be sent at symbol periods 6 and 5, respectively, in each of subframes 0 and 5 of each radio frame with the normal cyclic prefix, as shown in FIG. 2. UEs can use the sync signals for cell detection and acquisition. The BS can send a physical broadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH can carry certain system information.

[0074] The BS may send a control format indicator physical channel (PCFICH) in only part of the first symbol period of each subframe, although it is represented in the entire first symbol period in FIG. 2. The PCFICH can transmit the number of symbol periods (M) used for the control channels, where M can be equal to 1,2 or 3 and can change from subframe to subframe. M can also be equal to 4 for a small system bandwidth, for example, with less than 10 resource blocks. In the example shown in FIG. 2, M = 3. The BS can send a HARQ indicator physical channel (PHICH) and a downlink control physical channel (PDCCH) in the first M symbol periods of each subframe (M = 3 in FIG. 2 ). The PHICH may carry information to support Automatic Hybrid Relay (HARQ). The PDCCH can carry information about the uplink and downlink resource allocation for the UEs and power control information for the uplink channels. Although they are not shown in the first symbol period in FIG. 2, it is understood that the PDCCH and PHICH are also included in the first symbol period. Similarly, both the PHICH and PDCCH are also in the second and third symbol periods, although they are not shown that way in FIG. 2. The BS may send a downlink shared physical channel (PDSCH) in the remaining symbol periods of each subframe. The PDSCH can carry data for UEs scheduled for data transmission on the downlink. The various signals and channels in LTE are described in 3GPP TS36.211, entitled "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation" which is available to the public.

[0075] The BS can send the PSS, the SSS and the PBCH in the central 1.08 MHz of the system bandwidth used by node B. The BS can send the PCFICH and PHICH across the entire bandwidth of the system in each symbol period in which these channels are sent. The BS can send the PDCCH to groups of UEs in certain portions of the system bandwidth. The BS can send the PDSCH to specific UEs in specific portions of the system bandwidth. BS can send PSS, SSS, PBCH, PCFICH and PHICH in broadcast form to all UEs, can send PDCCH in unicast form to specific UEs, and can also send PDSCH in unicast form to UE specific.

[0076] A number of resource items may be available in each symbol period. Each resource element can span a subcarrier in a symbol period and can be used to send a modulation symbol, which can be a real or complex value. The resource elements not used for a reference signal in each symbol period may be arranged in resource element groups (REG). Each REG can include four resource items in a symbol period. The PCFICH may occupy four REGs, which may be approximately evenly spaced along the frequency, in symbol period 0. The PHICH may occupy three REGs, which may be dispersed along the frequency, by one or plus configurable symbol periods. For example, the three REGs for the PHICH may all belong to symbol period 0 or they may be scattered across symbol periods 0, 1, and 2. The PDCCH may occupy 9, 18, 36, or 72 REG, for example, which are they can select from the available REG, in the first M symbol periods. Only certain REG combinations can be allowed for the PDCCH.

[0077] A UE may know the specific REGs used for the PHICH and the PCFICH. The UE can look up the PDCCH in different REG combinations. The number of combinations to search is typically less than the number of combinations allowed for the PDCCH. A BS can send the PDCCH to the UE in any of the combinations that the UE will look for.

[0078] A UE can be within the coverage of multiple BSs. One of these BSs can be selected to serve the UE. The serving BS can be selected based on various criteria such as received power, path loss, signal-to-noise ratio (SNR), etc.

In certain systems (eg, such as NR or 5G systems), a BS may transmit these or other signals at these locations or at different locations in the subframe.

[0080] FIG. 3 is a diagram 300 illustrating an example of an uplink (UL) frame structure in a wireless telecommunications system (eg, LTE). The resource blocks available to the UL can be divided into a data section and a control section. The control section can be formed at the two edges of the system bandwidth and can be configurable in size. The resource blocks of the control section can be assigned to the UEs for the transmission of control information. The data section can include all resource blocks not included in the control section. The UL frame structure results in the data section including contiguous subcarriers, which can allow all contiguous subcarriers in the data section to be assigned to a single UE.

[0081] A UE may be assigned resource blocks 310a, 310b in the control section to transmit control information to a BS. The UE may also be allocated resource blocks 320a, 320b in the data section to transmit data to the BS. The UE can transmit control information on a physical UL control channel (PUCCH) in the resource blocks allocated in the control section. The UE can transmit data only, or both data and control information, on a UL Shared Physical Channel (PUSCH) in the resource blocks allocated in the data section. A UL transmission can span both slots of a subframe and can perform frequency hopping.

[0082] A set of resource blocks can be used to perform an initial access to the system and achieve UL synchronization on a physical random access channel (PRACH) 330. The PRACH 330 carries a random sequence and cannot carry any data / UL marking. Each random access preamble can occupy a bandwidth corresponding to six consecutive resource blocks. The network specifies the starting frequency. That is, the transmission of the random access preamble may be limited to certain time and frequency resources. There may be no frequency hopping for PRACH. The PRACH attempt can be carried in a single subframe (1 ms) or in a sequence of few contiguous subframes, and a UE can perform a single PRACH attempt per frame (10 ms). In some aspects, described herein, the PRACH and / or the SRS may be located at additional and / or different time and / or frequency resources.

In certain systems (for example, such as NR or 5G systems), a BS can transmit these or other signals at these locations or at different locations in the subframe.

[0084] FIG. 4 illustrates example components of the BS 110 and UE 120 of wireless network 100 illustrated in FIG. 1, which can be used to implement aspects of the present disclosure. One or more components of BS 110 and UE 120 can be used to implement aspects of the present disclosure. For example, antennas 452, Tx / Rx 222, processors 466, 458, 464, and / or controller / processor 480 of UE 120 can be used to perform the operations described herein and illustrated with reference to FIGS. . 15, 17 and 19, and / or antennas 434, processors 440, 420, 438, and / or controller / processor 440 of the BS 110 can be used to perform the operations described herein and illustrated with reference to FIGS. 16 and 18.

[0085] FIG. 4 shows a block diagram of a design of a BS 110 and a UE 120, which may be one of the BSs and one of the UEs of FIG. 1. For a restricted association scenario, BS 110 may be macro BS 110c of FIG. 1, and the UE 120 can be the UE 120y. The BS 110 can also be a base station of some other type. The BS 110 can be equipped with antennas 434a to 434t and the UE 120 can be equipped with antennas 452a to 452r.

[0086] In the BS 110, a transmit processor 420 may receive data from a data source 412 and control information from a controller / processor 440. The control information may be for the PBCH, PCFICH the, the PHICH, the PDCCH, etc. The data can be for the PDSCH, etc. Processor 420 can process (eg, code and assign symbols) the data and control information to obtain data symbols and control symbols, respectively. Processor 420 can also generate reference symbols, for example, for PSS, SSS, and cell specific reference signal. A transmit (TX) multiple input multiple output (MIMO) processor 430 can perform spatial processing (e.g., precoding) on data symbols, control symbols, and / or reference symbols, if applicable, and can provide output symbol streams to modulators (MOD) 432a through 432t. Each modulator 432 can process a respective output symbol stream (eg, for OFDM, etc.) to obtain an output sample stream. Each modulator 432 can further process (eg, analog, amplify, filter, and frequency up) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t can be transmitted via antennas 434a through 434t, respectively.

[0087] At UE 120, antennas 452a through 452r the can receive downlink signals from BS 110 and may provide received signals to demodulators (DEMOD) 454a through 454r, respectively. Each demodulator 454 can condition (eg, filter, amplify, down-frequency, and digitize) a respective received signal to obtain input samples. Each demodulator 454 can further process the input samples (eg, for OFDM, etc.) to obtain received symbols. A MIMO detector 456 can obtain received symbols from all demodulators 454a through 454r, perform MIMO detection on received symbols, if applicable, and provide detected symbols. A receive processor 458 can process (eg, demodulate, deinterlace, and decode) the detected symbols, provide decoded data for the UE 120 to a data collector 460, and provide decoded control information to a controller / processor 480.

[0088] In the uplink, at UE 120, a transmit processor 464 may receive and process data (e.g., for the PUSCH) from a data source 462 and control information (for example, for the PUCCH) from the controller / processor 480. Transmission processor 464 may also generate reference symbols for a reference signal. The symbols from the transmit processor 464 can be precoded by a TX MIMO processor 466, if applicable, further processed by the demodulators 454a to 454r (eg, for SC-FDM, etc.) and transmitted to the BS 110. In BS 110, the uplink signals from UE 120 can be received by antennas 434, processed by modulators 432, detected by a MIMO detector 436, if applicable, and further processed by a receive processor 438 to obtain the decoded data. and the control information sent by the UE 120. The receiving processor 438 may provide the decoded data to a data collector 439 and the decoded control information to the controller / processor 440.

[0089] Controllers / processors 440 and 480 can direct operation in BS 110 and UE 120, respectively. Processor 440 and / or other processors and modules in BS 110 may also perform or direct, for example, the execution of the functional blocks illustrated in FIGS. 16, 18 and / or other processes for the techniques described herein. Processor 480 and / or other processors and modules in UE 120 can perform or direct, for example, the execution of the functional blocks illustrated in FIGS. 15, 17, 19 and / or other processes for the techniques described herein. Memories 442 and 482 can store data and program codes for BS 110 and UE 120, respectively. A scheduler 444 may schedule one or more UEs for data and / or control transmissions on the downlink and / or uplink.

[0090] FIG. 5 is a diagram 500 illustrating an example of a radio protocol architecture for user and control planes in certain systems (eg, LTE). The radio protocol architecture for the UE and the BS is shown with three layers: Layer 1, Layer 2 and Layer 3. Layer 1 (L1 layer) is the lowest layer and implements various physical layer signal processing functions. . In this document, Layer L1 will be referred to as physical layer 506. Layer 2 (L2 layer) 508 is above physical layer 506 and is responsible for the link between the UE and the BS on physical layer 506.

[0091] In the user plane, the layer L2508 includes, for example, a sublayer of access control means (MAC) 510, a control sublayer radio link (RLC) 512 and a sublayer of convergence protocol packet data (PDCP) 514, which is terminated at the BS on the network side. Although not shown, the UE It can have several upper layers on top of the L2 layer 508, including a network layer (for example, an IP layer) that ends at PDN gateway 118 on the network side, and an application layer that ends on the other. end of the connection (for example, a far-end UE, server, etc.).

[0092] The PDCP sublayer 514 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 514 also provides overhead compression for higher layer data packets to reduce radio transmission overhead, security by encrypting data packets, and handover capability for UEs between BSs. The RLC sublayer 512 provides higher layer data packet segmentation and reassembly, retransmission of lost data packets, and data packet reordering to compensate for messy reception due to a hybrid automatic repeat request (HARQ). MAC sublayer 510 provides multiplexing between logical and transport channels. The MAC sublayer 510 is also responsible for allocating the various radio resources (eg, resource blocks) of a cell among the UEs. The MAC sublayer 510 also handles HARQ operations.

[0093] In the control plane protocol architecture radio to the UE and the BS is substantially the same for the physical layer 506 and layer L2508, with the exception that no function is header compression for control plane. The control plane also includes a radio resource control (RRC) sublayer 516 at Layer 3 (L3 layer). The RRC sublayer 516 is responsible for obtaining radio resources (ie, radio bearers) and for configuring the lower layers using RRC signaling between the Node B and the UE.

[0094] FIG. 6 shows two exemplary subframe formats 610 and 620 for the downlink with the normal cyclic prefix. The time-frequency resources available for the downlink can be divided into resource blocks. Each resource block can span 12 subcarriers in a slot and can include a number of resource elements. Each resource element can span a subcarrier in a symbol period and can be used to send a modulation symbol, which can be a real or complex value.

[0095] The subframe format 610 can be used for a BS equipped with two antennas. A CRS can be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11. A reference signal is a signal that is known a priori by a transmitter and a receiver, and can also be called a pilot. . A CRS is a reference signal that is specific to a cell, for example it is generated based on a cell identity (ID). In FIG. 6, for a given resource element labeled Ra, a modulation symbol on that resource element can be transmitted from antenna to, and no modulation symbol on that resource element can be transmitted from other antennas. The 620 subframe format can be used for a BS equipped with four antennas. A CRS can be transmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11 and from antennas 2 and 3 in symbol periods 1 and 8. For both 610 and 620 subframe formats, you can transmit a CRS on uniformly separated subcarriers, which can be determined based on the cell ID. Different BSs can transmit their CRS on the same subcarrier or on different subcarriers, depending on their cell IDs. For both 610 and 620 subframe formats, resource elements not used for CRS can be used to transmit data (eg, traffic data, control data, and / or other data).

[0096] PSS, SSS, CRS and PBCH in LTE are described in 3GPP TS 36,211 entitled "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation", which is available to the public.

[0097] You can use an intercalation structure for each of the downlink and uplink FDD (for example, LTE). For example, interleaved Qs can be defined with indices from 0 to Q-1, where Q can be equal to 4, 6, 8, 10 or some other value. Each collation can include subframes that are separated by Q frames. In particular, the interleaving q may include the subframes q, q Q, q 2Q, etc., where qe {0, ..., Q -1}.

[0098] The wireless network can support Hybrid Automatic Relay (HARQ) for data transmission on the downlink and on the uplink. For HARQ, a transmitter (eg, BS) can send one or more transmissions of a packet until a receiver (eg, UE) correctly decodes the packet or some other termination condition is experienced. For synchronous HARQ, for example, all packet transmissions can be sent in single interleaved subframes. For asynchronous HARQ, for example, each transmission of the packet can be sent in any subframe.

[0099] While aspects of the examples described herein may be associated with LTE technologies, aspects of the present invention may be applicable with other wireless communication systems, such as NR or 5G technologies.

[0100] New radio (NR) can refer to radios configured to operate in accordance with a new air interface (eg other than orthogonal frequency division multiple access (OFDMa) based air interfaces) or with a fixed transport layer (for example, other than Internet Protocol (IP)). The NR can use OFDM with a CP on the uplink and on the downlink and include support for half-duplex operation using TDD. NR can include Enhanced Mobile Broadband (eMBB) service that targets a wide bandwidth (for example, above 80 MHz), of the millimeter wave (mmW) that targets a high carrier frequency. (for example, 60 GHz), of the massive MTC (mMTC) that is directed to techniques of MTC not compatible with previous versions, and / or the critical mission that is directed to the service of ultra-reliable low latency communications (URLLC).

[0101] 100MHZ single component carrier bandwidth can be supported. The NR resource blocks can span 12 subcarriers with a subcarrier bandwidth of 75 kHz in a duration of 0.1 ms. Each radio frame can consist of 50 subframes with a length of 10 ms. Consequently, each subframe can be 0.2 ms long. Each subframe can indicate a link direction (ie DL or UL) for data transmission, and the link direction for each subframe can be dynamically switched. Each subframe can include DL / UL data as well as DL / UL control data. The UL and DL subframes for the NR may be as described in more detail below with respect to FIGS. 9 and 10.

[0102] Beam shaping can be supported and the beam direction can be dynamically configured. MIMO streams with precoding can also be supported. MIMO configurations on the DL can support up to 8 transmitting antennas with multi-layer DL streams of up to 8 streams and up to 2 streams per UE. Multilayer streams with up to 2 streams per UE can be supported. Multiple cell aggregation with up to 8 serving cells can be supported. Alternatively, the NR may support a different air interface, other than an OFDM-based interface. NR networks can include entities such as central units or distributed units

[0103] The RAN may include a central unit (CU) and distributed units (DU). An NR BS (eg gNB, 5G Node B, Node B, Transmit / Receive Point (PRT), Access Point (AP)) can correspond to one or multiple BSs. NR cells can be configured as access cells (cells A) or data-only cells (cells D). For example, the RAN (for example, a central unit or a distributed unit) can configure the cells. Cells D can be cells used for carrier aggregation or dual connectivity, but are not used for initial access, cell selection / reselection, or handover. In some cases, the D cells may not transmit sync signals; in some cases, D cells can transmit SS. NR BSs can transmit downlink signals to UEs indicating cell type. Based on the indication of the cell type, the UE can communicate with the BS of NR. For example, the UE may determine the NR BSs to be considered for cell selection, access, handover and / or metering based on the indicated cell type.

[0104] FIG. 7 illustrates an example logical architecture of a distributed RAN 700, in accordance with aspects of the present disclosure. A 5G Access Node 706 may include an Access Node Controller (ANC) 702. The ANC may be a Central Unit (CU) of Distributed RAN 700. The Return Interface to the Next Generation Core Network (NG-CN ) 704 may end in the ANC. The return interface to neighboring Next Generation Access Nodes (NG-AN) may terminate at the ANC. The ANC may include one or more TRP 708 (which may also be referred to as BS, NR BS, Node B, 5G NB, AP, or by some other term). As described above, a TRP can be used interchangeably with "cell".

[0105] TRP 708s can be a distributed unit (DU). TRPs can be connected to one ANC (ANC 702) or to more than one ANC (not illustrated). For example, for RAN sharing, Radio as a Service (RaaS), and service-specific ANC implementations, the TRP can connect to more than one ANC. A TRP can include one or more antenna ports. TRPs can be configured to allow individually (eg dynamic selection) or jointly (eg joint transmission) traffic to a UE.

[0106] The local architecture 700 can be used to illustrate the front end network definition. You can define the architecture that supports front end solutions in different types of deployment. For example, the architecture can be based on the capabilities of the transmission network (eg, bandwidth, latency, and / or jitter).

[0107] The architecture can share features and / or components with LTE. According to aspects, the Next Generation AN (NG-AN) 710 can support dual connectivity with NR. NG-AN can share a common front-end network for LTE and NR.

[0108] The architecture may allow cooperation between TRP 708. For example, cooperation may be preset within a TRP and / or between TRPs via ANC 702. Depending on the aspects, it may not be needed / present an interface between TRP.

[0109] According to the aspects, a dynamic configuration of split logic functions can be present within the architecture 700. The PDCP, RLC, MAC protocol can be adaptively placed in the ANC or in the TRP.

[0110] According to certain aspects, a BS can include a central unit (CU) (eg ANC 702) and / or one or more distributed units (eg one or more TRP 708).

[0111] FIG. 8 illustrates an example physical architecture of a distributed RAN 800, in accordance with aspects of the present disclosure. A centralized central network unit (C-CU) 802 can host central network functions. The C-CU can be implemented centrally. C-CU functionality can be downloaded (for example, to Advanced Wireless Services (AWS)), in an effort to handle maximum capacity.

[0112] A centralized RAN unit (C-RU) 804 can host one or more ANC functions. Optionally, the C-RU can host core network functions locally. The C-RU can have a distributed implementation. The C-RU may be closer to the edge of the network.

[0113] A distributed unit (DU) 806 can accommodate one or more TRPs. The DU may be located at the edges of the network with radio frequency (RF) functionality.

[0114] FIG. 9 is a diagram 900 showing an example of DL-centered subframe. The DL-centered subframe may include a control portion 902. The control portion 902 may exist in the beginning or beginning portion of the DL-centered subframe. Control portion 902 may include various scheduling information and / or control information corresponding to various portions of the DL-centered subframe. In some configurations, the control portion 902 may be a physical DL control channel (PDCCH), as indicated in FIG. 9. The DL-centered subframe may also include a DL 904 data portion. The DL 904 data portion may sometimes be referred to as a DL-centered subframe payload. The DL data portion 904 may include the communication resources used to communicate DL data from the scheduling entity (eg, the UE or BS) to the subordinate entity (eg, the UE). In some configurations, the data portion of DL 904 may be a PDCCH.

[0115] The DL-centered subframe may also include a common UL 906 portion. The common UL 906 portion may sometimes be referred to as a UL burst, common UL burst, and / or by various other suitable terms. Common UL portion 906 may include feedback information corresponding to various other portions of the DL-centered subframe. For example, common UL portion 906 may include feedback information corresponding to control portion 902. Non-limiting examples of feedback information may include an ACK signal, a NACK signal, a HARQ flag, and / or various other types of information. suitable. Common UL portion 906 may include additional or alternative information, such as information pertaining to random access channel procedures (RACH), scheduling requests (SR), and various other suitable types of information. As illustrated in FIG. 9, the end of the data part of d L 904 may be separated in time from the beginning of the common UL part 906. This separation in time can sometimes be called gap, guard period, guard interval, and / or with various other suitable terms. This separation provides time for switching from DL communication (eg, receive operation by the subordinate entity (eg UE)) to UL communication (eg transmission by the subordinate entity (eg UE) ). One skilled in the art will understand that the foregoing is merely an example of a DL-centered subframe and that alternative structures may exist that have similar characteristic features without necessarily deviating from the aspects described herein.

[0116] FIG. 10 is a diagram 1000 showing an example of a UL centered subframe. The UL-centered subframe may include a control portion 1002. The control portion 1002 may exist in the beginning or beginning portion of the UL-centered subframe. The control part 1002 in FIG. 10 may be similar to control portion 902 described above with reference to FIG. 9. The UL-centric subframe may also include a UL 1004 data portion. The UL 1004 data portion may sometimes be referred to as the UL-centric subframe payload. The UL part may refer to the communication resources used to communicate UL data from the subordinate entity (eg UE) to the scheduling entity (eg UE or BS). In some configurations, the control part 1002 may be a physical DL control channel (PDCCH).

[0117] As illustrated in FIG. 10, the end of the control part 1002 may be separated in time from the beginning of the UL data part 1004. This separation in time can sometimes be referred to as a gap, guard period, guard interval, and / or with various other suitable terms. This separation provides time for the switch from DL communication (eg, receive operation by the scheduling entity) to UL communication (eg, transmission by the scheduling entity). The UL-centered subframe may also include a common UL portion 1006. The common UL portion 1006 in FIG. 10 may be similar to the common UL 906 portion described above with reference to FIG. 9. Common UL part 1006 may include additional or alternative information pertaining to Channel Quality Indicator (CQI), Polling Reference Signals (SRS), and various other suitable types of information. One skilled in the art will understand that the foregoing is merely an example of a UL-centered subframe and that alternative structures may exist that have similar characteristic features without necessarily deviating from the aspects described herein.

[0118] In some circumstances, two or more subordinate entities (eg UE) may communicate with each other by side link signals. Real-world applications of such side-link communications can include public safety, proximity services, UE-to-network relay, vehicle-to-vehicle (V2V) communications, Internet of everything (IoE) communications, IoT communications, mesh mission critical and / or various other suitable applications. In general, a side link signal can refer to a signal communicated from a subordinate entity (eg, UE1) to another subordinate entity (eg, UE2) without relaying that communication through the scheduling entity (eg, UE or b S), although the scheduling entity can be used for scheduling and / or control purposes. In some examples, side link signals can be communicated using licensed spectrum (as opposed to wireless local area networks, which typically use unlicensed spectrum).

[0119] Advanced LTE UEs can use up to a 20 MHz spectrum of allocated bandwidth in an aggregation of carriers up to a total of 100 MHz (5 component carriers (CC)) used for transmission in each direction. For advanced LTE mobile systems, two types of carrier aggregation (CA) procedures have been proposed, continuous CA and non-continuous CA, illustrated in FIGS. 11 and 12, respectively. Continuous AC occurs when multiple available component carriers are adjacent to each other (FIG. 11). On the other hand, non-continuous AC occurs when multiple available component carriers are spaced across the frequency band (FIG. 12). Both non-continuous AC and continuous AC aggregate multiple component / LTE carriers to serve a single Advanced LTE UE unit. According to various embodiments, the UE operating in a multi-carrier system (also called carrier aggregation) is configured to aggregate certain multi-carrier functions, such as control and feedback functions, on the same carrier, which are may be referred to as "main carrier". The remaining carriers that depend on the primary carrier for their support are called associated secondary carriers. For example, the UE can add control functions such as those provided by the optional dedicated channel (DCH), unscheduled grants, a physical uplink control channel (PUCCH) and / or a physical downlink control channel. (PDCCH).

[0120] In certain systems (for example, LTE systems operating according to version 13 of the wireless standards and higher), a UE can be configured with up to 32 DC for AC, for example. Each CC can be up to 20 MHz in size (for example, and can be backward compatible). Therefore, up to 640 MHz of bandwidth can be configured for a UE (for example, 32 CC x 20 MHz per CC).

[0121] DC to AC can all be configured as Frequency Division Duplexing (FDD) DC, all as Time Division Duplexing (TDD) DC, or configured as a mix of FDD DC and TDD DC. Different TDD CCs may have the same or different downlink and uplink (DL / UL) configurations. Special subframes can also be configured differently for different TDD CCs.

[0122] In an example AC configuration, one DC can be configured as the primary DC (for example, referred to as the P cell or PCC) for the UE and at most one other DC can be configured as the primary secondary DC (for For example, named as cell Sp). Only cell P and cell Sp can carry the physical uplink control channel (PUCCH). The UE can monitor the common search space only in cell P. All other CCs can be referred to as secondary CCs (SCCs). CCs can be configured for uplink only, downlink only, or both uplink and downlink.

[0123] The SRS is a reference signal transmitted by the UE in the uplink direction. The SRS can be used in the BS to estimate the quality of the uplink channel in a wider bandwidth. In the case of TDD, the BS can also use the SRS to estimate the downlink channel (eg due to channel reciprocity). The BS can use this information for selective uplink frequency scheduling for both downlink and uplink. However, in cases where the UE is configured with one or more aggregate CCs that are configured for downlink only (e.g. not configured for at least PUSCH / PUCCH transmission), it may not be possible to exploit reciprocity. channel if the UE is not allowed to transmit the SRS on downlink-only carriers.

[0124] Therefore, certain systems (eg version 14 or later of LTE systems) can support switching SRS to and between DC. SRS switching can be supported when the UE has fewer CCs available for PUSCH carrier aggregation (for example, compared to the number of CCs available for PDSCH carrier aggregation). In these cases, the CCs available for SRS transmission may correspond to the CCs available for PDSCh carrier aggregation (eg, aggregated downlink-only CCs). For example, assume that a UE is configured with five aggregated CCs (CC1, CC2, CC3, CC4, and CC5), where CC1 is the PCC and is configured for broadcasts downlink / uplink, and the CC2-CC5s are SCC and configured for downlink-only transmissions. In this example, the CCs available for SRS transmission (in SRS switching) are the SCCs CC2-CC5.

[0125] SRS switching may involve the UE (eg a UE having a single transmission chain) switching between transmissions on one (eg first) CC to SRS transmission on a different CC (eg , downlink only), and then back to the first CC. Continuing with the previous example, the UE can perform SRS switching to one or more of the SCCs CC2-CC5 from the PCC CC1 or from another of the SCCs CC2-CC5. The SRS switching may involve a switching time to switch between transmitting on the first CC to transmitting the SRS on the other CC and switching back to the first CC. The switching can be between different TDD DCs, different FDD DCs, TDD and FDD DCs, etc. The particular CCs between which the UE switches as well as the capabilities of the UE can affect the switching time involved in the SRS switching.

[0126] FIG. 13 is a block diagram illustrating example uplink and downlink subframes for two CCs, in accordance with certain aspects of the present disclosure. As shown in FIG. 13, the UE can be configured with at least the TDD CC1 (eg, the PCC) and the TDD CC2. CC2 can be a TDD carrier configured for DL only. That is, in one example, the CC2 may not be configured for PUSCH / PUCCH transmissions. For example, as shown in FIG. 13, for TDD CC2, subframes 0, 4, 5, 9 are configured as downlink subframes; subframes 1 and 6 are configured as special subframes; and subframes 2, 3, 7, 8 are inactive uplink subframes (eg, whereas for CC1, subframes 2, 3, 7, 8 are active uplink subframes). However, as described above, one or more of the resources described above can be allocated and / or used in a different way. For example, in some aspects, the SRS for CC2 may be transmitted in the idle uplink subframes (eg, to exploit channel reciprocity) in CC2 (eg, in subframe 7 in the example shown in FIG. 13).

[0127] In some cases, SRS transmissions on CC2 may coincide with other transmissions, such as PUSCH or PUCCH on CC1. In such cases, the SRS transmission on CC2 may interrupt the transmission on CC1. Alternatively or additionally, the transmission of SRS in CC2 can be discarded. FIG. 14 is a block diagram illustrating example SRS switching with interference, in accordance with certain aspects of the present disclosure. In the example shown in FIG. 14, the transmission of SRS in CC2 can cause the UE 120 to ignore, delete, puncture, discard and / or not process one or more symbols of the PUSCH or PUCCH in CC1. For example, as shown in FIG. 14, if the UE 120 has a switching time (e.g. including retune time) of 2 symbols, a total of 5 symbols can be ignored, deleted, punctured, discarded and / or not processed on CC1 due to interrupt of UE communication on CC1 to switch between CC1 and CC2 to transmit SRS on CC2.

EXAMPLE PRACH AND / OR SRS SWITCHING IMPROVEMENT

[0128] In general, SRS transmissions from UEs in the network should be orthogonal to SRS transmissions from other UEs in the network. To maintain orthogonality in the network, SRS transmissions from UEs to a particular BS in the network should arrive at the BS at the same time (or within a CP length). Therefore, the UE may attempt to transmit a PRACH to obtain an initial timing advance (TA) estimate for the SRS transmission.

[0129] However, when the UE is configured to perform CA mode SRS switching with a PCC and one or more downlink-only SCCs, the UE may have to transmit the PRACH on the downlink-only SCC ( for example, in a manner similar to that transmitted by SRS in the downlink-only SCC). The UE can do this, for example, in cases where the PCC for cell P and SCC for cell S belong to different timing advance groups (t Ag) and therefore have different TA values (for example, because cell P associated with the PCC is not positioned with cell S associated with the SCC). In such cases, the BS (eg, to set a TA for cell S) can trigger the UE to transmit a PRACH in cell S by transmitting a PDCCH command (eg, in cell P) to the UE.

[0130] However, in cases where the UE has a limited number of transmission chains (for example, the UE may have a transmission chain), the transmission of PRACH in cell S may interrupt communication in the cell P (eg, similarly to when SRS transmissions in cell S interrupt communication in cell P as shown in FIG. 14). Depending on the configuration and position (for example, the location of the symbol within a subframe) of PRACH, this interruption can have a significant impact on the performance of the P-cell. For example, the interruption due to transmission of PRACH can create additional interrupt or interrupts in the previous and / or subsequent subframes in cell P.

[0131] The aspects presented herein, for example, provide techniques to reduce the impact of switching due to transmission of PRACH and / or SRS.

[0132] In one aspect, the techniques presented herein can be used to improve PRACH transmission in the uplink pilot timeslot (UpPTS).

[0133] In certain systems, for example, such as LTE, a subframe format may include an UpPTS. Using a 10 ms radio frame as a reference example, the 10 ms radio frame can include two half frames of equal length (e.g. 5 ms), with each half frame consisting of 10 slots or 8 slots plus three special fields: DwPTS (downlink pilot timeslot), GP (guard period) and UpPTS in a special subframe. In this example, each slot can be 0.5 ms long and two consecutive slots can form a subframe. The special subframe (including UpPTS) can be used to switch between uplink and downlink subframes, for example during TDD operation.

[0134] In LTE version 13, UpPTS can be used for up to six symbols (eg Sc -f Dm A symbols). In some aspects, an Ue can use UpPTS to transmit PRACH, Sr S and / or PUSCH, etc. In some cases, a PRACH of two to four symbols may be sufficient to allow the BS to determine the TA estimate. Consequently, the aspects presented in this document may allow the transmission of PRACH in the first symbols of UpPTS (for example, excluding one or more of the last symbols of the UpPTS) to reduce the impact on a CC (for example, PCC or SCC) due to switching to another CC when transmitting p RAc H.

[0135] FIG. 15 is a flow chart illustrating example operations 1500 for wireless communications, in accordance with certain aspects of the present disclosure. Operations 1500 can be performed, for example, by a UE (eg, UE 120). It should be noted that the steps described in the dashed boxes (for example, at 1504, 1506, 1508, 1510, and 1516) correspond to optional steps that can be performed as part of operations 1500.

[0136] Operations 1500 can start at 1502 where the UE determines, based on one or more conditions, whether to use one or more symbols of an UpPTS for transmission of a PRACH to a BS (eg BS 110). For example, the UE can use up to six UpPTS symbols for a PRACH transmission. In addition, a PRACH of two to four symbols may be sufficient to allow the BS to determine the uplink TA for the SCC. In some aspects, the UE may determine whether to use the first (start) symbols of UpPTS for transmission of PRACH in the SCC (for example, as opposed to the last symbols of UpPTS). For example, assuming two symbols are used for PRACH, the UE can determine whether to use the first two UpPTS symbols or any two UpPTS symbols (excluding the last or last two UpPTS symbols). It should be noted that while a two-symbol PRACH is used herein as a reference example, the techniques presented herein can also be applied for a three- or four-symbol PRACH.

[0137] In 1504, the UE may signal an indication of the ability to use one or more UpPTS symbols for transmission of a PRACH to the BS. For example, the UE may determine that it has the ability (eg the UE may support version 14 or later) to transmit the PRACH in the first (eg at least two) symbols or symbols that exclude one or more of the Last (for example, last two) UpPTS symbols. The UE may inform the BS (eg, flag an indication) of its ability to transmit the PRACH in one or more symbols (eg, first symbols) of the UpPTS. In one aspect, the one or more conditions (eg, at 1502) may be based in part on whether the UE has the ability to use one or more UpPTS symbols for a PRACH transmission.

[0138] At 1506, the UE may receive from the BS an indication or configuration to transmit the PRACH in one or more (eg, first) UpPTS symbols. The UE, for example, may receive the indication or configuration in response to signaling (eg, at 1504) that it has the ability to use the first UpPTS symbols for PRACH transmission. In one aspect, the one or more conditions (eg, at 1502) may be based in part on whether the UE receives an indication or configuration from the BS to use one or more UpPTS symbols for PRACH transmission. In one aspect, the UE may receive the indication or configuration via RRC signaling. The indication or setting can be sent as unicast as opposed to broadcast.

[0139] In 1508, the UE may monitor a PDCCH command (eg, from the BS) for PRACH transmission. The PDCCH command can activate the UE to initiate a random access procedure with the BS transmitting a PRACH. The PDCCH command can be transmitted, for example, in situations where the UE is not in sync with the BS, the UE needs an initial (or updated) TA for use in uplink transmissions to the BS, etc. The PDCCH command can be sent using one of one or more predetermined DCI formats. The UE, in turn, may monitor the one or more DCI formats for the PDCCH command before transmitting the PRACH to the BS.

[0140] In 1510, the UE can determine the resource allocation information to transmit the PRACH in based on the PDCCH command. For example, the PDCCH command may include at least part of the resource allocation for the PRACH. The resource allocation information may indicate at least one of a time position for PRACH transmission (e.g., first two symbols, two middle symbols, last two UpPTS symbols, assuming a two symbol PRACH), a frequency position (eg the set of 6 physical resource blocks within the system bandwidth) for PRACH transmission, and / or power control information for PRACH transmission. In one aspect, the power control information may indicate at least one of a number of attempts to transmit PRACH or an amount of transmit power to be used for each number of attempts.

[0141] At 1512, the UE breaks communication in a first CC to switch from the first CC to a second CC. For example, the UE may have a limited number of transmission chains (eg, a single transmission chain). In such cases, the UE may have to interrupt communication on the first CC to retune its transmission chain to the second CC to transmit the PRACH on the second CC. The UE may transmit a PRACH on the second CC in cases where the second CC is a downlink-only SCC that does not have an uplink TA established (for example, for the UE to use for an SRS transmission later in the SCC).

[0142] In 1514, after switching to the second CC, the UE transmits the PRACH on the UpPTS based on the determination. For example, if the UE receives a configuration or indication to use the first UpPTS symbols for PRACH transmission, the UE may transmit the PRACH in the first indicated UpPTS symbols. The UE can also transmit the PRACH according to the resource allocation information received by means of a PDCCH command (eg, at 1510). Transmission of PRACH in the first UpPTS symbols in the second CC can reduce the amount of interruption of the first CC.

[0143] In 1516, after transmitting the PRACH, the UE may monitor another PDCCH command (from the BS) before repeating the PRACH transmission. For example, after transmitting the PRACH on the second CC, the UE can retune the first CC (eg, PCC) or another SCC to monitor a RAR from the BS. If the RAR is not detected, the UE can stay in the first CC to monitor another PDCCH command, as opposed to switching back to the second CC to automatically retransmit a PRACH (based on a number of allowed PRACH attempts determined to starting from the initial PDCCH command). In this way, the UE can further reduce the amount of first CC interrupt that may be associated with repeated switching to the second CC for multiple PRACH attempts.

[0144] FIG. 16 is a flow chart illustrating example operations 1600 for wireless communications, in accordance with certain aspects of the present disclosure. Operations 1600 can be performed, for example, by a BS (eg, BS 110). It should be noted that the steps described in the dashed line boxes (eg, at 1604 and 1608) correspond to optional steps that can be performed as part of operations 1600.

[0145] Operations 1600 can start at 1602 where the BS determines, based on one or more conditions, whether to configure a UE to use one or more symbols from an UpPTS for transmission of a PRACH to the BS. For example, in some cases, a PRACH of two to four symbols may be sufficient to allow the BS to determine the uplink TA for the SCC. The BS may determine whether to configure the Ue to use the first (start) symbols of a six symbol UpPTS for transmission of PRACH in the SCC (for example, as opposed to one or more of the last symbols of the UpPTS).

[0146] In 1604, the BS may receive an indication of a UE ability to use one or more (eg, first symbols) of an UpPTS for PRACH transmission. The UE may inform the BS (eg, flag an indication) of its ability to transmit the PRACH in one or more symbols (eg, first symbols) of the UpPTS. In one aspect, the one or more conditions (eg, in 1602) may be based in part on whether the BS receives the indication of the UE's capability. In one aspect, the one or more conditions (eg, at 1602) may be based in part on whether the UE has the ability to use one or more UpPTS symbols for a PRACH transmission.

[0147] In 1606, the BS transmits an indication of the determination to the UE. In one aspect, the BS may transmit an indication or configure the UE to transmit the PRACH in the first UpPTS symbols after receiving an indication (eg, at 1604) that the UE has the ability to use one or more symbols of UpPTS for a PRACH broadcast. However, in some aspects, even if the BS does not receive an indication of the capability of the UE, the BS may configure the UE to transmit the PRACH in one or more symbols (eg, the first symbols) of UpPTS. The BS may configure the UE to transmit the PRACH in the first UpPTS symbols by means of RRC signaling. The BS may configure the UE in unicast form (eg, as opposed to broadcast) to transmit the PRACH.

[0148] In 1608, the BS may transmit a PDCCH command for PRACH transmission to the UE. The PDCCH command can activate the UE to initiate a random access procedure with the BS transmitting a PRACH. The BS may transmit the PDCCH command in situations where the BS determines that the UE is not synchronized, the UE needs an initial (or updated) TA for the SCC, etc. The PDCCH command can be sent using one or more predetermined DCI formats. In some aspects, the PDCCH command may include at least part of the resource allocation for the PRACH. For example, the resource allocation may indicate at least one of a time position for PRACH transmission, a frequency position for PRACH transmission, or power control information for PRACH transmission. The power control information may indicate the number of PRACH attempts allowed and / or an amount of transmit power to be used for each PRACH attempt.

[0149] In 1610, the BS receives from the UE the PRACH transmitted in the UpPTS. In one aspect, the BS may receive the PRACH on the UpPTS via an SCC associated with the UE that is configured for downlink transmission only. The PRACH can be transmitted in accordance with the PDCCH command resource allocation information transmitted to the UE (eg, at 1608). The PRACH may allow the BS to determine a TA for the UE to use for subsequent SRS transmissions in the downlink-only SCC.

[0150] The aspects presented herein also provide techniques for improving the random access (RA) procedure, eg for SRS switching.

[0151] For example, the conventional random access procedure (eg for the PDCCH command, without contention) generally involves the following steps: (1) the UE monitors the PDCCH command from a BS; (2) if a PDCCH command is detected, the UE transmits the PRACH to the BS; (3) the UE monitors a random access response (RAR) from the BS; (4) if a RAR is detected (eg, with a corresponding Random Access Preamble Identifier (RAPID) field for the UE), the RA procedure is completed; (5) otherwise, if a RAR is not detected, the UE performs a power increase (for example, increases the PRACH transmit power level and repeats the PRACH transmission according to the number of PRACH attempts allowed from PDCCH command (eg step 2)).

[0152] In some cases, however, the UE may not detect a RAR from the BS after transmitting the PRACH. For example, if the UE and the BS are out of sync, a RAR may have been transmitted, but the Ue may not be able to decode the RAR. In another example, the BS may not detect the PRACH and therefore cannot transmit a RAR to the UE. However, with the above procedure, if the UE does not detect a RAR from the BS, the UE can autonomously decide to transmit another PRACH to the BS. Every time the UE decides to transmit the PRACH, the UE may have to interrupt the PCC to switch to an SCC to transmit the PRACH. As a result, the use of the above procedure can be highly ineffective in the context of SRS switching as repeated PRACH transmissions can cause significant interruptions in the PCC or the originating carrier, in general. Consequently, it may be desirable to improve the random access procedure, eg for SRS switching.

[0153] FIG. 17 is a flow chart illustrating example operations 1700 for wireless communications, in accordance with certain aspects of the present disclosure. Operations 1700 can be performed, for example, by a UE (eg, UE 120). It should be noted that the steps described in the dashed line boxes (for example, at 1708) correspond to optional steps that can be performed as part of operations 1700.

[0154] Operations 1700 can start in 1702 where the UE monitors a first PDCCH command for a first PRACH transmission. The first PDCCH command can trigger the UE to transmit the first PRACH. The UE may monitor one or more predetermined DCI formats for the first PDCCH command. The PDCCH command may include at least resource allocation information for PRACH transmission.

[0155] In 1704, the UE can determine a transmit power for the first PRACH transmission. In one aspect, the UE can determine the transmit power based on an indicator received in the first PDCCH command. For example, the resource allocation information (from the first PDCCH command) may include at least power control information for PRACH transmission. The power control information may indicate at least one of a number of allowed attempts (eg, preambleTransMax) to transmit / repeat the PRACH or an amount of transmit power to be used for each PRACH attempt. The power control indicator (in the first order of PDCCH) may indicate an absolute power control value or a power control value relative to one or more power control values for one or more previous PRACH transmissions. In one aspect, the UE may determine the transmission power based on a retransmission index of the first PRACH transmission. For example, the UE may increase the transmit power for each PRACH attempt according to a power increase that is based in part on the PRACH retransmission index.

[0156] In 1706, the UE transmits the first PRACH at the determined transmit power. For example, to transmit the PRACH, the UE can break communication in a first CC (eg, PCC or Cc) to switch from the first CC to a second CC. After switching to the second DC, the Ue can transmit the PRACH on the second DC. The second CC can be a CC that is configured for link transmission downstream only (for example, DC is not configured for at least PUSCH / PUCCH transmissions).

[0157] In 1708, the UE can monitor a RAR after transmitting the first PRACH. For example, in some aspects, the UE may switch back to the first CC or another SCC to monitor the RAR from the BS. If a RAR is detected, the random access procedure can be completed. For example, the RAR may include a TA value for the UE to use to adjust its uplink timing for uplink transmissions (eg, such as SRS). If a RAR is not detected, the UE can increase the transmit power and attempt another PRACH transmission (eg, assuming the UE is below the maximum number of retransmission attempts allowed).

[0158] In 1710, after transmitting the first PRACH, the UE monitors a second PDDCH command before transmitting a second PRACH. For example, in some respects, the UE may use the legacy random access procedure described above, but instead of automatically transmitting the next PRACH (for example, in response to not detecting an rAr), the UE may monitor another PDCCH command. from the BS before transmitting the next PRACH. That is, the UE can monitor a RAR after transmitting the first PRACH and if the RAR is not detected, monitor another (e.g. second) order of PDCCH instead of automatically repeating the PRACH transmission according to the number of attempts at the first PDCCH command. Once the second PDCCH command is received, the UE can transmit a second PRACH (eg, associated with the second PDCCH command) with increased power (determined from the second PDCCH command). In some cases, the UE may transmit the second PRACH with an increased power determined in accordance with a power increase stage (eg, increasing the power over the previous first PRACH transmission). In other words, using the legacy procedure above as a reference example, the UE can perform stage 1 after stage 5, instead of stage 2 after stage 5.

[0159] According to certain aspects, the UE (eg at 1706) can be configured to send a single PRACH transmission without increasing power. For example, the UE (eg at 1702) can be configured (via the first PDCCH command) with a parameter associated with a preamble transmission threshold such as preambleTransMax set to 1.

[0160] In certain aspects, in addition to being configured to send a single PRACH transmission, the UE may determine (eg, at 1704) a transmit power for the single PRACH transmission. For example, in one case, the BS may cause the RRC to reconfigure the UE with a new value for P_0 or a similar parameter associated with an initial transmit power for the single PRACH transmission. In one case, the BS may send a power control indicator to the UE (eg, by means of the indicator received in the first PDCCH command) to indicate the value of the transmit power for the single PRACH transmission. The power control indicator can indicate an absolute power control value or a relative (eg, or incremental) power control value.

[0161] According to certain aspects, the UE may receive (eg at 1702) an explicit indication from the BS of the number of PRACH attempts allowed and / or the power control values that are used for each PRACH attempt . The explicit indication, for example, can be received in cases where the UE is configured to transmit on a CC that is not configured for PUSCH / PUCCH transmissions. The UE may receive (at 1702) a command (eg, PDCCH command) or a grant within downlink control information (DCI) indicating the number of attempts. In some cases, the number of attempts may be set to 1. Additionally or alternatively, in one aspect, the command or grant within the DCI may include the power control value (for example, the amount of transmit power ) that is used for each PRACH transmission. Said power control value can be an absolute power control value (for example, a power control value, such as 10 dB, etc. relative to an open-loop power control value) or a value of relative power control (eg, a value relative to one or more power control values for one or more previous PRACH transmissions) (eg, cumulative across different triggers). In some cases, the power control flag may have a sufficient number of bits (eg 3-4 bits) to allow larger power control settings.

SAMPLE GROUP DCI FOR SRS ACTIVATION

[0162] For certain networks (eg, LTE), in some aspects, a group DCI may jointly trigger SRS transmissions and / or perform power control of SRS transmissions.

[0163] In general, there may be a field in the DCI grant that indicates which CCs are activated for SRS transmissions. In one case, the UE may receive a bitmap (eg, with one bit per CC) indicating which CCs are activated. Assuming that the UE is configured with four Ccs and receives the bitmap "0101", the UE can determine that CC2 and C4 are activated for SRS transmissions. In one case, the UE can receive a trigger for one carrier at a time. Thus, assuming the UE is configured with eight CCs, the UE can receive a 3-bit field within the DCI grant indicating which of the eight CCs are activated.

[0164] However, activating SRS transmissions in this way can be ineffective. For example, in case a bitmap is used, for UEs configured with a large number of CCs, the bitmap field may have a large number of bits (for example, 32 bits for a UE configured with 32 DC). On the other hand, activating SRS transmissions from a single DC at a time may have reduced flexibility.

[0165] Accordingly, it may be desirable to provide improved techniques for activating SRS transmission and / or performing power control for SRS transmissions. As described below, the techniques presented herein allow a BS to trigger SRS transmissions from multiple UEs, trigger SRS transmissions from multiple CCs from the same UE at the same time, and / or perform separate power control for each CC configured for a UE.

[0166] FIG. 18 is a flow chart illustrating example operations 1800 for wireless communications, in accordance with certain aspects of the present disclosure. Operations 1800 can be performed, for example, by a BS (eg, BS 110). It should be noted that the steps described in the dashed boxes (for example, in 1806, 1810, 1812, 1814, and 1816) correspond to optional steps that can be performed as part of operations 1800.

[0167] Operations 1800 can begin in 1802 where the BS identifies a plurality of CCs available for at least one UE to use for SRS transmissions to the BS. The UE, for example, can be configured with a plurality of added CCs. Each of the CCs can be configured for downlink transmission only, uplink transmission only, or for both downlink and uplink transmission. The UE may be capable of sending SRS transmissions in CC downlink only, CC uplink only or CC that support both downlink / uplink transmissions. The BS can identify from the configuration in which of the CCs the UE can send SRS transmissions.

[0168] In 1804, the BS determines a configuration that specifies one or more CCs of the plurality of CCs that at least one UE must use for SRS transmissions. In one aspect, the configuration may specify one or more CCs for use by a single UE for SRS transmissions. In one aspect, the configuration may specify one or more CCs for use by multiple UEs for SRS transmissions. In one aspect, the configuration may specify one or more different CCs for the respective different groups of UEs that are used for SRS transmissions.

[0169] In 1806, the BS may determine one or more SRS trigger groups for configuration. Each SRS group may include one or more CCs of the plurality of CCs, identified by the BS (eg, at 1802), that the at least one UE is to use for SRS transmissions. In some cases, each group of SRS may include one or more different CCs from the plurality of CCs. Each SRS group can have multiple SRS transmissions from the group's CCs, and the order of the CCs can be indicated. One or more CCs in each SRS group can be CCs configured for downlink transmission only. In a reference example, the UE can be configured with SRS group 1: {CC1, CC3, CC4}, SRS group 2: {CC4, CC2}, SRS group 3: {CC1}, and group 4: { CC4, CC5, CC6}. It should be noted that the example of four SRS groups is provided as a reference example and that a UE can be configured with any number of SRS groups.

[0170] In 1808, the BS may signal a configuration indication to at least one UE. In one aspect, the BS may configure the UE with the SRS trigger group set (eg, at 1806) via RRC signaling.

[0171] In 1810, the BS can trigger SRS transmissions from the UE by means of one or more CCs in one of the SRS groups. Continuing with the previous example of four SRS trigger groups, the BS can use a 2-bit field in the group DCI to trigger SRS transmissions in one of the four SRS groups. Assuming that the 2-bit field comprises "11", the UE can be activated to transmit SRS transmissions via CC4, CC5 and CC6 (eg in SRS group 4). However, in general, the size of the field can be based on the number of SRS groups configured for the UE (eg, via RRC signaling). For example, the field size (for example, in bits) in the group DCI can be equal to ceil (log2 (Ngroups)).

[0172] Additionally, at 1812, the BS may perform power control for one or more CCs in the group activated for SRS transmissions (eg, at 1810). For example, the BS may provide power commands for at least one of the C's in the activated SRS group of the SRS groups via the group DCI, and the number of fields for the power control commands in The group DCI can be based in part on which of the SRS groups has the highest number of CCs. Continuing with the previous example of four SRS trigger groups, since the maximum number of CCs among the four groups is three CCs, the BS can use three fields within the group d C i to provide power control for CC in the activated group. In cases where the number of CCs in an activated group is less than the number of fields in the group DCI (for example, in the case of group 3 above), the BS may use a smaller number of fields assigned to provide power control commands for the DCs in the activated group (for example, the BS may include a power control command in a single field (of the three fields in the DCI) for the CC1 in group 3). In some cases, the number of fields for power control commands may be equal to the number of CCs in the activated SRS group. In some cases, the number of fields for power control commands may equal a number of CCs in the activated SRS group that are configured for downlink transmission only.

[0173] In 1814, the BS may alternatively provide a single transmit power command for one of the CCs in the activated SRS group (eg, in 1810). In one aspect, for example, the BS may indicate (eg, via RRC signaling) which CC is affected by the transmit power command. In one aspect, the determination of which CC is affected may be implicit (eg, according to a predefined rule or configuration). For example, the UE may implicitly determine to use the TPC for the first CC in the SRS group. In one aspect, the number of transmit power commands and the corresponding DCs to which they are applied can be configured by RRC.

[0174] According to certain aspects, in 1816, the BS can simultaneously trigger SRS transmissions from multiple CCs of the plurality of CCs configured for the at least one UE. In one aspect, the configuration (eg, at 1804) may indicate multiple CCs of the plurality of CCs for the at least one UE, and the indication (eg, at 1808) of the configuration can simultaneously trigger SRS transmissions from the at least one UE of the multiple CCs. For example, the BS may trigger SRS transmissions from multiple CCs by means of one or more groups of fields in the group DCI. Assuming, for example, that the BS wants to activate 2 CCs at the same time, the BS can include 2 groups of fields in the group DCI, each group including a field to indicate which CC is activated and a field to indicate the TPC command to DC activated. For example, if a UE is configured with 8 CCs (CC1-CC8), the Bs can trigger the UE to transmit the SRS from CC4 by means of a first group, which includes a three-bit field to indicate CC4 and another field with one or bits to indicate the TPC command for CC4, and activate the UE to transmit the SRS from CC5 by means of a second group, which includes a three-bit field to indicate CC5 and another field with one or bits to indicate the TPC command for CC5. It should be noted that the example of simultaneous transmissions from two CCs is provided as a reference example, and that a BS, using the techniques presented herein, can trigger a UE to simultaneously transmit the SRS from any number of CCs.

[0175] According to certain aspects, the configuration (eg, in 1804) may be associated with one or more group radio network temporary identifiers (G-RNTI) configured for the at least one UE. For example, the UE can be configured or associated with more than one G-RNTI so that different CCs and / or groups of c C can be activated in different G-RNTI DCIs. Thus, assuming the UE is configured with two G-RNTIs, the UE can monitor a first configuration (having a first set of SRS trigger groups) based on the group DCI associated with G-RNTI_1 and a second configuration (having a second set of SRS activating groups) based on the group DCI associated with G-RNTI_2. In certain aspects, the UE may monitor a G-RNTI DCI that configures the UE with a set of SRS trigger groups (e.g., as in 1806), and monitor another G-RNTI DCI that simultaneously triggers SRS transmissions from the UE by means of multiple CCs of the plurality of CCs (eg, as in 1816).

[0176] According to certain aspects, the configuration (eg at 1804) and / or the G-RNTI configuration may be associated with a subframe configuration for the at least one UE. That is, when configuring the G-RNTI and / or the CC set, the configuration may be sub-frame dependent or sub-frame associated. In a reference example, the BS may activate a first set of CCs in a first subframe and activate a second set of CCs in a second subframe. In one example, the BS may provide a TPC command for CC1 in a first subframe and provide a TPC command for CC2 in a second subframe. In some cases, the position of the UE / C C (eg UE / CC information) in the total number of bits may also depend on the subframe or be associated with the subframe. Additionally or alternatively, the set of CCs and UEs present in the group DCI may be subframe dependent or associated with the subframe.

[0177] According to certain aspects, the UE may monitor the new group DCI for SRS triggers / TPC commands in addition to the legacy DCI (eg DCI3 / 3A format for TPC commands only). For example, the UE may receive RRC configuration signaling (eg via BS at 1808) indicating whether the power control information for a given CC is in the new group DCI or in DCI3 / 3A, or both. Additionally, the BS may include an additional 2-bit TPC command in the DL grant for SRS.

[0178] According to certain aspects, for group DCI, different UEs may have different bit widths depending on their RRC configuration. For example, if UE 1 has 2 Ce and UE 2 has 4 CC, then the bit width of UE 2 can be approximately twice the size of UE 1.

[0179] FIG. 19 is a flow chart illustrating example operations 1900 for wireless communications, in accordance with certain aspects of the present disclosure. Operations 1900 can be performed, for example, by a UE (eg, UE 120). It should be noted that the stages described in the dashed line boxes (for example, in 1904, 1906 and 1908) correspond to optional stages that are can be performed as part of 1900 operations.

[0180] Operations 1900 can start in 1902 where the UE receives a trigger to transmit an SRS on each CC of a group of one or more CCs to one or more corresponding BSs (eg, one or more BS 110). In one aspect, the UE may receive group DCIs that activate the UE to transmit an SRS from one or more CCs in one of the multiple SRS groups configured for the UE. For example, the UE may receive a 2-bit field in the group DCI that activates a particular group of one or more CCs. Each CC in the activated group can be a CC that is configured for downlink transmission only, uplink transmission only, or both uplink and downlink transmissions.

[0181] In 1904, the UE may receive a configuration indicating a plurality of groups of one or more CCs. For example, the UE may receive, via RRC signaling, a set of SRS trigger groups. Each SRS trigger group may include one or more CCs (eg, different) of a plurality of CCs that are configured for SRS transmissions. In one aspect, the activator (eg, at 1902) may include an indication of the CC group (eg, the SRS activator group) of the plurality of groups. That is, the group DCI (eg in 1902) can activate one of the SRS groups indicated in the received configuration.

[0182] In 1906, the UE may receive one or more power control commands for at least one of the DCs in the group of one or more DCs. The UE may receive the trigger (eg, in 1902) and power control commands by means of a command or grant in the DCI (eg, the group DCI). For example, the UE can receive power commands for at least one of the Cc's in the SRS group activated via the group DCI, and the number of fields for the power control commands in the group DCI can be based in part on which of the SRS groups configured for the UE has the highest number of CCs. In some aspects, the number of fields for power control commands may equal the number of CCs in the activated SRS group. In some aspects, the number of fields for power control commands may equal a number of CCs in the activated SRS group that are configured for downlink transmission only.

[0183] In 1908, the UE may receive an indication that simultaneously triggers the transmission of an SRS from multiple CCs. In one aspect, the UE may receive one or more groups of fields in the group DCI, where each group of fields corresponds to a particular CC activated for SRS transmission. For example, each group in the group DCI may include a field to indicate which Cc is activated and a field to indicate the t Pc command for the activated CC.

[0184] In 1910, the UE transmits SRS to the BSs in response to the trigger. To transmit each SRS, the UE may interrupt transmission on a first CC, switch to the activated CC (s), and transmit the SRS on the activated CC (s). The activated CC (s) may be a CC that is configured for downlink transmission only.

[0185] The specific order or hierarchy of disclosed process steps is understood to be an illustration of exemplary approaches. Based on design preferences, it is understood that the specific order or hierarchy of the process stages can be rearranged. Also, some stages can be combined or skipped. The accompanying procedural claims present elements of the various steps in sample order and are not intended to be limited to the specific order or hierarchy presented.

[0186] As used herein, a phrase that refers to "at least one of" a list of items refers to any combination of those items, including individual members. As an example, "at least one of: a, b, oc" is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination with multiples of the same element (for example, aa, aaa, aab, aac, abb, acc, bb, bbb, bbc, cc, and ccc or any other ordering of a, b, and c). On the other hand, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise specified, or is clear from the context, the term "X uses A or B" is intended to mean any of the natural inclusive permutations. That is, the expression "X uses A or B" is satisfied in any of the following cases: X uses A; X uses B; or X employs both A and B. In addition, the articles "a" and "an", as used in this application and in the appended claims, should be construed, generally, to mean "one or more. ", unless otherwise specified or clear from the context that they refer to a singular form.

[0187] The procedures disclosed herein comprise one or more steps or actions to achieve the described procedure. The process steps and / or actions can be interchanged with each other without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of specific steps and / or actions can be modified without departing from the scope of the claims.

[0188] As used herein, the term "determine" encompasses a wide variety of actions. For example, "determine" may include calculate, compute, process, derive, investigate, query (for example, query a table, database, or other data structure), find out, and the like. Furthermore, "determining" can include receiving (eg, receiving information), accessing (eg, accessing data in a memory), and the like. In addition, "determine" can include solve, select, choose, set, and the like.

[0189] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications of these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other aspects. Therefore, it is not intended to limit the claims to the aspects set forth herein, but should be granted the full scope consistent with the language of the claims, in which reference to an element in the singular is not intended to mean "one and only one ", unless specifically manifested so, but rather" one or more ". Unless specifically stated otherwise, the term "some" refers to one or more. All structural and functional equivalents of the elements of the various aspects described throughout this disclosure that are known or will be known to those skilled in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly cited in the claims. No claim item should be construed in accordance with 35 USC § 112, paragraph six, unless the item is expressly referred to with the phrase "means to" or, in the case of a procedural claim, the item is referred to by the expression "stage to / from".

[0190] The various operations of the procedures described above can be performed by any suitable means that can perform the corresponding functions. The media can include various hardware and / or software components and / or modules, including, but not limited to, a circuit, an application-specific integrated circuit (ASIC), or a processor. In general, when there are features illustrated in the figures, those features may have corresponding equivalent media plus feature components with similar numbering.

[0191] For example, means to transmit, means to signal, means to configure, means to communicate, means to provide, means to repeat, means to send, means to increment and / or means to indicate may include transmission processor 420 , TX MIMO processor 430 and / or antenna (s) 434 of base station 110 illustrated in FIG. 4, and / or transmission processor 464, TX MIMO processor 466, and / or antenna (s) 452 of user equipment 120 illustrated in FIG. 4. Means for monitoring, means for receiving, means for communicating and / or means for detecting may include the receiving processor 438 and / or the antenna (s) 434 of the base station 110 illustrated in FIG. 4, and / or receiving processor 458 and / or antenna (s) 452 of user equipment 120 illustrated in FIG. 4. Means to monitor, means to determine, means to transmit, means to detect, means to abstain, means to interrupt, means to communicate, means to switch, means to receive, means to signal, means to repeat, means to identify, means to activate, means to indicate, means to provide, means to configure, means to send, means to increment and / or means to exchange may include one or more processors or other elements, such as the controller / processor 480 of the user equipment 120 illustrated in FIG. 4, and / or the controller / processor 440 of the base station 110 illustrated in FIG. Four.

[0192] The various illustrative logic blocks, modules and circuits described in connection with this disclosure can be implemented or realized with a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC) a programmable gate array (FPGA) or other programmable logic device (PLD), logic gates or discrete transistors, discrete hardware components or any combination thereof designed to perform the functions described herein. A general purpose processor can be a microprocessor, but alternatively, the processor can be any commercially available processor, controller, microcontroller, or state machine. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors together with a DSP core, or any other such configuration.

[0193] If implemented in hardware, an example hardware configuration may comprise a processing system on a wireless node. The processing system can be implemented with a bus architecture. The bus can include any number of interconnect buses and bridges, depending on the specific application of the processing system and global design constraints. The bus can link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface can be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter can be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1), a user interface (eg, keyboard, display, mouse, joystick, etc.) can also be connected to the bus. The bus can also link various other circuits, such as timing sources, peripheral devices, voltage regulators, power management circuits, and the like, which are well known in the art and therefore Therefore, they will not be described further. The processor can be implemented with one or more general-purpose and / or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuits that can run software. Those skilled in the art will recognize the best way to implement the described functionality for the processing system, depending on the particular application and the overall design constraints imposed on the overall system.

[0194] If implemented in software, the functions can be stored on, or transmitted on, a computer-readable medium, such as one or more instructions or code. Software should be broadly interpreted to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including running software modules stored on the machine-readable storage media. A computer-readable storage medium can be coupled to a processor so that the processor can read information from, and write information to, the storage medium. Alternatively, the storage medium can be integrated into the processor. By way of example, the machine-readable media may include a transmission line, a data-modulated carrier wave, and / or a computer-readable storage medium with instructions stored therein separate from the wireless node, all of which can be accessed by the processor through the bus interface. Alternatively, or in addition, machine-readable media, or any part thereof, may be integrated into the processor, as may be the case with general cache and / or log files. Examples of machine-readable storage media may include, by way of example, RAM (random access memory), flash memory, ROM (read-only memory), PROM (programmable read-only memory), EPROM (memory-only). erasable and programmable read), EEPROM (electrically erasable programmable read-only memory), registers, magnetic disks, optical disks, hard disks or any other suitable storage medium or any combination thereof. Machine-readable media can be incorporated into a computer program product.

[0195] A software module can comprise a single instruction, or many instructions, and can be distributed over several different code segments, between different programs and across multiple storage media. Computer-readable media can comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules can include a transmitting module and a receiving module. Each software module can reside on a single storage device or it can be distributed across multiple storage devices. As an example, a software module can be loaded into an RM from a hard drive when a triggering event occurs. During the execution of the software module, the processor can load part of the instructions in cache memory to increase the access speed. One or more cache lines can then be loaded into a general log file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when it executes instructions from that software module.

[0196] Furthermore, any connection is appropriately referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared (IR ), radio and microwave, then coaxial cable, fiber optic cable, twisted pair, DSL or wireless technologies such as infrared, radio and microwave are included in the definition of medium. Discs, as used herein, include compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disc, and Blu-ray® disc, where some discs play normally the data is magnetic, while other discs reproduce the data optically with lasers. Thus, in some respects, computer-readable media may comprise non-transitory computer-readable media (eg, tangible media). In addition, for other aspects, the computer-readable media may comprise transient computer-readable media (eg, a signal). Combinations of the above should also be included within the scope of computer-readable media.

[0197] Thus, certain aspects may comprise a computer program product to perform the operations presented herein. For example, such a computer program product may comprise a computer-readable medium that has instructions stored (and / or encoded) therein, the instructions being executable by one or more processors to perform the operations described herein. . For example, instructions to determine the maximum available transmit power of the UE, instructions to semi-statically configure a first guaranteed minimum power available for uplink transmission to a first base station and a second minimum guaranteed power available for link transmission uplink to a second base station and instructions to dynamically determine a first maximum transmit power available for uplink transmission to the first base station and a second maximum transmit power available for uplink transmission to the second base station based on, at least in part, in the power of Maximum available transmission of the UE, the first guaranteed minimum power, and the second minimum guaranteed power.

[0198] Furthermore, it should be appreciated that modules and / or other appropriate means to perform the procedures and techniques described herein can be downloaded and / or otherwise obtained by a user terminal and / or a base station, as appropriate. For example, such a device can be attached to a server to facilitate the transfer of media to perform the procedures described herein. Alternatively, various methods described herein may be provided via storage media (eg, RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc.), so that a user terminal and / or a base station can obtain the various procedures after coupling or providing the storage media to the device. In addition, any other suitable technique can be used to provide a device with the procedures and techniques described herein.

[0199] The scope of the invention is limited only by the appended claims.

Claims (14)

1. A method (1800) for wireless communications through a base station, BS, comprising: identifying (1802) a plurality of component carriers, CC, available to at least one user equipment, UE, for use to transmit polling reference signals, SRS, to the BS; determining (1804) a configuration comprising a plurality of SRS groups, each SRS group specifying one or more different CCs from the plurality of CCs that the at least one UE must use for SRS transmissions; and signaling (1808) an indication of the configuration to the at least one UE. The method (1800) of claim 1, wherein the configuration is associated with one or more temporary group radio network identifiers, G-RNTIs configured for the at least one UE. The method (1800) of claim 1, wherein the indication of the configuration comprising the one or more SRS groups is signaled by means of radio resource control signaling, RRC. The method (1800) of claim 1, further comprising: triggering SRS transmissions from the at least one UE via one or more of the CCs in one of the SRS groups. The method (1800) of claim 4, wherein the one of the SRS groups is indicated by means of a command or grant in downlink control information, DCI. The method (1800) of claim 5, further comprising: provide power control commands for at least one of the DCs in the one of the SRS groups via the DCI. The method (1800) of claim 6, wherein a number of fields for power control commands in the DCI is based in part on which of the one or more groups of s Rs has a greater number of CCs. . The method (1800) of claim 4, further comprising: provide a single power control command for one of the DCs in the one of the SRS groups. The method (1800) of claim 1, wherein the configuration indicates multiple CCs of the plurality of CCs for the at least one UE. The method (1800) of claim 9, wherein the configuration indication simultaneously triggers SRS transmissions from at least one Ue in the multiple CCs. The method (1800) of claim 1, wherein at least one of the plurality of CCs is a CC configured for downlink transmission only. 12. An apparatus for wireless communication, comprising means for performing all the steps of the method (1800) of any one of claims 1 to 11. The apparatus of claim 12, wherein the means comprises a processing system. A computer program comprising program instructions that are computer executable to implement all steps of the method (1800) of any one of claims 1 to 11.